U.S. patent application number 15/104901 was filed with the patent office on 2016-10-27 for driving system.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Kenji Honda, Shigeru Nakayama.
Application Number | 20160312873 15/104901 |
Document ID | / |
Family ID | 53402800 |
Filed Date | 2016-10-27 |
United States Patent
Application |
20160312873 |
Kind Code |
A1 |
Nakayama; Shigeru ; et
al. |
October 27, 2016 |
DRIVING SYSTEM
Abstract
A driving system includes a drive source for driving a left
drive portion and a right drive portion, a power transmission
mechanism having a first and second differential mechanisms each
including a first rotating element, a second rotating element and a
third rotating element and a switching unit. The first rotating
elements of the first and second differential mechanisms are
connected to each other so as to rotate in the same direction, the
second rotating elements of the first and second differential
elements are connected to the left drive portion and the right
drive portion, respectively, and the third rotating elements of the
first and second differential mechanism are connected toe ach other
so as to rotate in opposite directions.
Inventors: |
Nakayama; Shigeru;
(Wako-shi, JP) ; Honda; Kenji; (Wako-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
53402800 |
Appl. No.: |
15/104901 |
Filed: |
December 16, 2014 |
PCT Filed: |
December 16, 2014 |
PCT NO: |
PCT/JP2014/083186 |
371 Date: |
June 15, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60K 6/365 20130101;
B60Y 2400/82 20130101; B60Y 2400/80 20130101; F16H 48/36 20130101;
Y10S 903/916 20130101; B60Y 2200/92 20130101; F16H 48/10 20130101;
F16H 2048/106 20130101; B60K 6/52 20130101; B60Y 2400/73 20130101;
F16H 2048/104 20130101; Y10S 903/911 20130101 |
International
Class: |
F16H 48/10 20060101
F16H048/10; B60K 6/52 20060101 B60K006/52; B60K 6/365 20060101
B60K006/365 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2013 |
JP |
2013-259429 |
Claims
1. A driving system comprising: a drive source, which drives a left
driving portion that is disposed on a left side of a vehicle with
respect to a traveling direction and a right driving portion that
is disposed on a right side of the vehicle with respect to the
traveling direction; and a power transmission mechanism, which has
a first differential mechanism and a second differential mechanism,
each having a first rotating element, a second rotating element,
and a third rotating element, wherein: the first rotating elements
of the first and second differential mechanisms are connected to
each other so as to rotate integrally in a same direction; the
second rotating elements of the first and second differential
mechanisms are connected to the left driving portion and the right
driving portion, respectively; the third rotating elements of the
first and second differential mechanisms are connected to each
other so as to rotate in opposite directions; and the power
transmission mechanism comprises a switching unit that switches
selectively between a first connected state where the drive source
and the first rotating elements of the first and second
differential mechanisms are connected and a second connected state
where the drive source and the third rotating elements of the first
and second differential mechanisms are connected.
2. The driving system according to claim 1, wherein: the power
transmission mechanism comprises: a first switching mechanism that
can switch between an applied state where a power transmission path
between the drive source and the first rotating elements of the
first and second differential mechanisms is connected and a
released state where the power transmission path between the drive
source and the first rotating elements of the first and second
differential mechanisms is disconnected; and a second switching
mechanism that can switch between an applied state where a power
transmission path between the drive source and the third rotating
elements of the first and second differential mechanisms is
connected and a released state where the power transmission path
between the drive source and the third rotating elements of the
first and second differential mechanisms is disconnected; and the
power transmission mechanism is configured to switch between a
first state where the first switching mechanism is in the applied
state while the second switching mechanism is in the released state
and a second state where the first switching mechanism is in the
released state while the second switching mechanism is in the
applied state.
3. The driving system according to claim 2, wherein the first
switching mechanism and the second switching mechanism are switched
between the applied state and the released state by a same
operating device.
4. The driving system according to claim 3, wherein the first
switching mechanism and the second switching mechanism are disposed
on a same rotational axis.
5. The driving system according to claim 4, wherein the first
rotating elements of the first and second differential mechanisms
are disposed on the rotational axis.
6. The driving system according to claim 2, wherein the first
switching mechanism and the first rotating elements of the first
and second differential mechanisms are disposed on a same
rotational axis.
7. The driving system according to claim 6, wherein the first
switching mechanism and the second switching mechanism are disposed
in positions that are offset in a radial direction and are disposed
in positions that overlap in an axial direction.
8. The driving system according to claim 1, wherein the drive
source is disposed on a side opposite to the second differential
mechanism with respect to the first differential mechanism in an
axial direction or on a side opposite to the first differential
mechanism with respect to the second differential mechanism in the
axial direction, and in a position that is offset from the first
and second differential mechanism in the axial direction.
9. The driving system according to claim 8, wherein the drive
source is disposed in a position that overlap the first and second
differential mechanisms in the radial direction.
10. The driving system according to claim 1, wherein: the switching
unit switches to the first connected state when a speed of the
vehicle is slower than a predetermined speed; and the switching
unit switches to the second connected state when the speed of the
vehicle is equal to or faster than the predetermined speed.
11. The driving system according to claim 10, wherein the driving
system is connected to an energy delivery and receipt unit that
executes at least one of a supply of energy to the drive source and
a recovery of energy from the drive source; the energy delivery and
receipt unit includes a first energy delivery and receipt unit and
a second energy delivery and receipt unit; the drive source is
connected to the first energy delivery and receipt unit and the
second energy delivery and receipt unit in a switchable fashion;
the first energy delivery and receipt unit is connected to another
drive source that is different from the drive source so as to
recover energy from the another drive source; and the second energy
delivery and receipt unit includes an energy storage unit.
12. The driving system according to c-laim 11, wherein: the drive
source is connected to the first energy delivery and receipt unit
when the speed of the vehicle is slower than the predetermined
speed; and
Description
TECHNICAL FIELD
[0001] The present invention relates to a driving system and more
particularly to a driving system that includes a drive source and
two differential mechanisms.
BACKGROUND ART
[0002] A power transmission mechanism is conventionally know which
includes a drive source and two planetary gear mechanisms. For
example, a driving force distribution system 100 described in
Patent Literature 1 includes, as show in FIG. 21, two planetary
gear mechanisms PL each including a ring gear R, planetary gears P,
a planetary carrier C and a sun dear S and two power sources having
a drive motor 102 that gives a driving force to a shaft 101 that
connects together the sun gears S of the two planetary gear
mechanisms PL and a control motor 103 that generates a difference
in driving force between left and right wheels. Then, according to
the description of Patent Literature 1, the driving force
distribution system 100 can be controlled so that a driving force
sum of the left and right wheels that influences a front-rear
motion (behavior) of a wheeled vehicle is given by driving the
drive motor 102 while by driving the control motor 103 as required
while running by means of the driving force of the drive motor 102,
a driving force difference of the left and right wheels that
influences a turning motion (behavior) of the wheeled vehicle is
given.
[0003] Namely, the driving force distribution system 100 described
in Patent Literature 1 includes the two power sources (the drive
motor 102, the control motor 103) and can control simultaneously
both the driving force sum of the left and right wheels that
influences mainly the front-rear motion (behavior) of the wheeled
vehicle and the driving force difference of the left and right
wheels that influences mainly the turning motion (behavior) of the
wheeled vehicle.
[0004] Additionally Patent Literature 2 discloses a left and right
wheel coupling unit in which a transmission system including two
gears is provided at one side of a bevel differential gear that is
connected to a motor and a transmission system including two gears
and a transmission system including three gears are provided via a
switching device at the other side of bevel differential gear. In
the transmission system including the two gears that is provided at
the other side of the bevel differential gear, a gear ratio thereof
is set to be the same as that of the transmission system including
the two gears that is provided at the one side of the bevel
differential gear. In the transmission system including the three
gears that is provided at the other side of the bevel differential
gear, a gear ratio thereof is set to be the same as that of the
transmission system including the two gears that is provided at the
one side of the bevel differential gear, these two gear rations
being opposite to each other in working direction and equal to each
other in absolute value. According to this coupling unit, when the
transmission system including the two gears is selected by the
switching device, the torque of the motor is transmitted to the
left and right wheels in the same direction and in the same
magnitude, whereby a forward start or a reverse start can be
assisted. When the transmission system including the three gears is
selected, the torque of the motor is transmitted to the left and
right wheels in the opposite directions and in the same magnitude,
whereby a turning assist can be provided in which a yaw moment is
generated in a turning direction.
PRIOR ART LITERATURE
Patent Literature
[0005] Patent Literature 1: JP-A-2010-144762
[0006] Patent Literature 2: Japanese Patent No. 3599847
SUMMARY OF THE INVENTION
Problem that the Invention is to Solve
[0007] However, with the driving force distribution system 100 of
Patent Literature 1, the two power sources are needed, the
increased production costs have to be involved, and the enlargement
in size of the system is inevitable. Thus, there is still room for
improvement. Additionally, with the coupling unit of Patent
Literature 2, the absolute values of the gear ratios are the same
whether the starting assist or the turning assist is performed, and
hence, a large difference in magnitude cannot be given between the
front-rear assist and the turning assist. Thus, there is still room
for improvement.
[0008] The invention provides a driving system in which a control
to give a driving force sum to a left driving portion and a right
driving portion and a control to give a driving force difference
between the left driving portion and the right driving portion can
be switched to one or the other with a single drive source and
magnitudes of absolute values of the driving force sum and the
driving force difference that are given to the same power of the
drive source can be set separately and independently.
Means for Solving the Problem
[0009] The present invention provides the following aspects.
[0010] According to a first aspect there is provided a driving
system (e.g., a rear wheel driving system 20 in embodiment)
including:
[0011] a drive source (e.g., a motor MOT in embodiment), which
drives a left driving portion (e.g., a left rear wheel LWr in
embodiment) that is disposed on a left side of a vehicle (e.g., a
wheeled vehicle V in embodiment) with respect to a traveling
direction and a right driving portion (e.g., a right rear wheel RWr
in embodiment) that is disposed on a right side of the vehicle with
respect to the traveling direction; and
[0012] a power transmission mechanism (e.g., a power transmission
mechanism TM2 in embodiment), which has a first differential
mechanism (e.g., a first planetary gear mechanism PL1 in
embodiment) and a second differential mechanism (e.g., a second
planetary gear mechanism PL2 in embodiment), each having a first
rotating element, a second rotating element, and a third rotating
element, wherein:
[0013] the first rotating elements of the first and second
differential mechanisms are connected to each other so as to rotate
integrally in a same direction;
[0014] the second rotating elements of the first and second
differential mechanisms are connected to the left driving portion
and the right driving portion, respectively;
[0015] the third rotating elements of the first and second
differential mechanisms are connected to each other so as to rotate
in opposite directions; and
[0016] the power transmission mechanism includes a switching unit
(e.g., first and second clutches CL1, CL2 in embodiment) that
switches selectively between a first connected state where the
drive source and the first rotating elements of the first and
second differential mechanisms are connected and a second connected
state where the drive source and the third rotating elements of the
first and second differential mechanisms are connected.
[0017] In addition to the configuration of the first aspect, a
second aspect is characterized in that:
[0018] the power transmission mechanism includes:
[0019] a first switching mechanism (e.g., the first clutch CL1 in
embodiment) that can switch between an applied state where a power
transmission path between the drive source and the first rotating
elements of the first and second differential mechanisms is
connected and a released state where the power transmission path
between the drive source and the first rotating elements of the
first and second differential mechanisms is disconnected; and
[0020] a second switching mechanism (e.g., the second clutch CL2 in
embodiment) that can switch between an applied state where a power
transmission path between the drive source and the third rotating
elements of the first and second differential mechanisms is
connected and a released state where the power transmission path
between the drive source and the third rotating elements of the
first and second differential mechanisms is disconnected; and
[0021] the power transmission mechanism is configured to switch
between a first state where the first switching mechanism is in the
applied state while the second switching mechanism is in the
released state and a second state where the first switching
mechanism is in the released state while the second state mechanism
is in the applied state.
[0022] In addition to the configuration of the second aspect, a
third aspect is characterized in that
[0023] the first switching mechanism and the second switching
mechanism are switched between the applied state and the released
state by a same operating device (e.g., an actuator in
embodiment).
[0024] In addition to the configuration of the third aspect, a
fourth aspect is characterized in that
[0025] the first switching mechanism and the second switching
mechanism are disposed on a same rotational axis.
[0026] In addition to the configuration of the fourth aspect, a
fifth aspect is characterized in that
[0027] the first rotating elements of the first and second
differential mechanisms are disposed on the rotational axis.
[0028] In addition to the configuration of the second or third
aspect, a sixth aspect is characterized in that
[0029] the first switching mechanism and the first rotating
elements of the first and second differential mechanisms are
disposed on a same rotational axis.
[0030] In addition to the sixth aspect, a seventh aspect is
characterized in that
[0031] the first switching mechanism and the second switching
mechanism are disposed in positions that are offset in a radial
direction and are disposed in positions that overlap in an axial
direction.
[0032] In addition to the configuration according to any one of the
first to seventh aspects, an eighth aspect is characterized in
that
[0033] the drive source is disposed on one side or the other side
of the first and second differential mechanisms in an axial
direction.
[0034] In addition to the configuration of the eighth aspect, a
ninth aspect is characterized in that
[0035] the drive source is disposed on a side opposite to the
second differential mechanism with respect to the first
differential mechanism in the axial direction or on a side opposite
to the first differential mechanism with respect to the second
differential mechanism in the axial direction, and in a position
that is offset from the first and second differential mechanism in
the axial direction.
[0036] In addition to the configuration of any one of the first to
ninth aspects, a tenth aspect is characterized in that:
[0037] the switching unit switches to the first connected state
when a speed of the vehicle is slower than a predetermined speed;
and
[0038] the switching unit switches to the second connected state
when the speed of the vehicle is equal to or faster than the
predetermined speed.
[0039] In addition to the configuration of the tenth aspect, an
eleventh aspect is characterized in that:
[0040] the driving system is connected to at energy delivery and
receipt unit that executes at least one of a supply of energy to
the drive source and a recovery of energy from the drive
source;
[0041] the energy delivery and receipt unit includes a first energy
delivery and receipt unit (e.g., a generator GEN, at capacitor CAP
in embodiment) and a second energy delivery and receipt unit (e.g.,
a battery BATT in embodiment);
[0042] the drive source is connected to the first energy delivery
and receipt unit and the second energy delivers and receipt unit in
a switchable fashion;
[0043] the first energy delivery and receipt unit is connected to
another drive source (e.g., an engine ENG in embodiment) that is
different from the drive source so as to recover energy from the
another drive source; and
[0044] the second energy delivery and receipt unit includes an
energy storage unit (e.g., a battery BATT in embodiment).
[0045] In addition to the configuration of the eleventh aspect, a
twelfth aspect is characterized in that:
[0046] the drive source is connected to the first energy delivery
and receipt unit when the speed of the vehicle is slower than the
predetermined speed; and
[0047] the drive source is connected to the second energy delivery
and receipt unit when the speed of the vehicle is equal to or
faster than the predetermined speed.
[0048] According a thirteenth aspect, the third rotating elements
of the first and second differential mechanisms are connected to
each other via an odd number of times of meshing occurring
therebetween.
Advantage of the Invention
[0049] According the first aspect, with the single drive source,
the driving force can be applied to the two driving portions in the
same direction or the driving force can applied so the two driving
portions in opposite directions. Then, for example in the event
that the driving system is mounted on a vehicle, a control to give
a driving force sum to left and right wheels and a control to
create a driving force difference between the left and right wheels
can be switched to one or the other. In addition, the magnitudes of
absolute values of the driving force sum and the driving force
difference that are given by the same power of the drive source can
be set separately and independently.
[0050] According to the second aspect, the power transmission path
between the drive source and the third rotating elements is
disconnected when the drive source and the first rotating elements
are connected together and the power transmission path between the
drive source and the first rotating elements is disconnected when
the drive source and the third rotating elements are connected
together. Thus, the power can be transmitted either to the first
rotating elements or to the third rotating elements in an ensured
fashion.
[0051] According to the third aspect, since the two switching
mechanisms can be controlled by the same operating device, not only
can it easily be avoided that both the first switching mechanism
and the second switching mechanism are put in the applied state,
but also the number of components involved can be reduced compared
with a case where two separate operating devices are provided for
the two switching mechanisms, thereby making it possible to
suppress the production costs.
[0052] According to the fourth aspect, the first switching
mechanism and the second switching mechanism can be disposed while
suppressing the expansion of the radial dimension of the driving
system.
[0053] According to the fifth aspect, since the first switching
mechanism and the second switching mechanism are disposed in line
with the first rotating elements of the first and second
differential mechanisms, the first switching mechanism and the
second switching mechanism can be disposed, for example, by making
use of a space defined between the first and second differential
mechanisms.
[0054] According to the sixth aspect, since the first switching
mechanism is disposed in line with the first rotating elements of
the first and second differential mechanisms, the first switching
mechanism can be disposed, for example, by making use of the space
defined between the first and second differential mechanisms.
[0055] According to the seventh aspect, the first switching
mechanism and the second switching mechanism can be disposed while
suppressing the expansion of the axial dimension of the driving
system.
[0056] According to the eighth aspect, compared with a case where
the drive source is disposed so as to be held between the first and
second differential mechanisms, the connecting portions between the
left and right driving portions and the second rotating elements
can be shifted inwards in a vehicle's width direction. Therefore,
an angle defined from the connecting portion to the wheel or a
wheel side member can be restrained from being increased.
[0057] According to the ninth aspect, the radial dimension can also
be reduced.
[0058] According to the tenth aspect, the two driving portions can
be driven in the same direction when the speed of the vehicle is
slower than the predetermined speed, while the two driving portions
can be driven in the opposite directions when the speed of the
vehicle is equal to or faster than the predetermined speed.
Therefore, it is possible to give assist in a case where a large
front-rear driving force is required as when the wheeled vehicle
starts and travels at low speeds and to effect torque vectoring to
improve a vehicle's steering performance.
[0059] According to the eleventh aspect, since the dove source is
connected to the first energy deliver and receipt unit that can be
connected to the another drive source and the storage unit in a
switchable fashion, the connecting destination of the drive source
can be selected according to situations.
[0060] According to the twelfth aspect, since a large driving force
is needed when the vehicle starts or travels at low speeds, the
drive source is driven with electric power generated by the first
energy delivery and receipt unit that can be connected to the
another drive source, and since only less electric power is needed
when the torque vectoring is effected at vehicle speeds equal to or
faster than the predetermined speed than when the vehicle starts or
travels at low speeds, the drive source can be driven with electric
power of the storage unit.
[0061] According to the thirteenth aspect, the third rotating
elements of the first and second differential mechanisms can easily
be connected so as to rotate is the opposite directions.
BRIEF DESCRIPTION OF DRAWINGS
[0062] FIG. 1 is a schematic block diagram of a wheeled vehicle
according to an embodiment on which a driving system of the
invention can be mounted.
[0063] FIG. 2 is a skeleton diagram of a rear wheel driving system
of a first embodiment.
[0064] FIG. 3A is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the wheeled vehicle travels straight ahead by a
front-wheel drive (FWD).
[0065] FIG. 3B is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the wheeled vehicle turns by front-wheel drive
(FWD).
[0066] FIG. 3C is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 3A when the wheeled
vehicle travels straight ahead by front-wheel drive (FWD).
[0067] FIG. 3D is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 3B when the wheeled
vehicle turns by front-wheel drive (FWD).
[0068] FIG. 4A is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the wheeled vehicle travels straight ahead by
four-wheel drive (4WD).
[0069] FIG. 4B is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the vehicle turns by four-wheel drive (4WD).
[0070] FIG. 4C is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 4A when the wheeled
vehicle travels straight ahead by four-wheel drive (4WD).
[0071] FIG. 4D is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 4B when the wheeled
vehicle turns during four-wheel drive (4WD).
[0072] FIG. 5A is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the wheeled vehicle travels straight ahead by
torque vectoring drive (TV).
[0073] FIG. 5B is a diagram showing a power transmission path and a
collinear chart in the rear wheel driving system of the first
embodiment when the wheeled vehicle turns by torque vectoring drive
(TV).
[0074] FIG. 5C is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 5A when the wheeled
vehicle travels straight ahead by torque vectoring drive (TV).
[0075] FIG. 5D is a skeleton diagram showing rotating elements in
the rear wheel driving system shown in FIG. 5B when the wheeled
vehicle turns by torque vectoring drive (TV).
[0076] FIG. 6 is a diagram showing flows of electric power when the
wheeled vehicle travels by 4WD drive and torque vectoring
drive.
[0077] FIG. 7 is a skeleton diagram of a rear wheel driving system
of a first modified example of the first embodiment.
[0078] FIG. 8 is a skeleton diagram of a rear wheel driving system
of a second modified sample of the first embodiment
[0079] FIG. 9 is a skeleton diagram of a rear wheel driving system
of a third modified example of the first embodiment.
[0080] FIG. 10 A is a diagram showing a power transmission path and
a collinear chart in the rear wheel driving system of the third
modified example of the first embodiment when the wheeled vehicle
travels by front-wheel drive (FWD).
[0081] FIG. 10B is a skeleton diagram showing rotating elements in
the rear wheel driving system of the third modified example of the
first embodiment when the wheeled vehicle travels straight ahead by
front-wheel drive (FWD).
[0082] FIG. 11A is a diagram showing a power transmission path and
a collinear chart in the rear wheel driving system of the third
modified example of the first embodiment when the wheeled vehicle
travels straight ahead by four-wheel drive (4WD).
[0083] FIG. 11B is a diagram showing rotating elements in the rear
wheel driving system of the third modified example of the first
embodiment when the wheeled vehicle travels straight ahead by
four-wheeled drive (4WD).
[0084] FIG. 12A is a diagram showing a power transmission path and
a collinear chart in the rear wheel driving system of the third
modified example of the first embodiment when wheeled vehicle
travels by torque vectoring drive (TV).
[0085] FIG. 12B is a skeleton diagram showing rotating elements in
the rear wheel driving system of the third modified example of the
first embodiment when the wheeled vehicle travels straight ahead by
torque vectoring drive (TV).
[0086] FIG. 13 is a skeleton diagram of a rear wheel driving system
of a fourth modified example of the first embodiment
[0087] FIG. 14 is a skeleton diagram of rear wheel driving system
of a fifth modified example of the first embodiment.
[0088] FIG. 15A is a skeleton diagram of a rear wheel driving
system of a second embodiment.
[0089] FIG. 15B shows collinear charts of the rear wheel driving
stem of the second embodiment.
[0090] FIG. 16A is a skeleton diagram of a rear wheel driving
system of a third embodiment.
[0091] FIG. 16B shows collinear charts of the rear wheel driving
system of the third embodiment.
[0092] FIG. 17 is a skeleton diagram of a rear wheel driving system
of a fourth embodiment.
[0093] FIG. 18A is a skeleton diagram of a rear wheel driving
system of a fifth embodiment.
[0094] FIG. 18B shows collinear charts of the rear wheel driving
system of the fifth embodiment.
[0095] FIG. 19 is a skeleton diagram of a rear wheel driving system
of a sixth embodiment.
[0096] FIG. 20 is a schematic block diagram of a wheeled vehicle
according to another embodiment on which the power transmission
system of the invention can be mounted.
[0097] FIG. 21 is a schematic block diagram of a conventional
driving force distribution system described in Patent Literature
1.
MODE FOR CARRYING OUT THE INVENTION
[0098] Firstly, referring to FIG. 1, a wheeled vehicle according to
an embodiment will be described on which a driving system of the
invention can be mounted.
[0099] As shown in FIG. 1, a wheeled vehicle V is a four-wheel
drive vehicle that includes a front wheel driving system 10 that
drives left and right front wheels LWf, RWf by the use of an engine
ENG via a power transmission mechanism TM1 and a rear wheel driving
system 20 that drives left and right rear wheels LWr, RWr by the
use of a motor MOT via a power transmission mechanism TM2.
[0100] In the front wheel driving system 10, the engine ENG is
connected to a generator GEN via a clutch CL, and the engine ENG
provides a thrusting force to the vehicle V as a main drive source.
The rear wheel driving system 20 assists the front wheel driving
system 10 and executes a front-rear traveling assist and a
left-right turning assist, which will both be described later, as
required by switching to one or the other of the assists. The motor
MOT of the rear wheel driving system 20 is connected selectively to
the generator GEN of the front wheel driving system 10 and a
battery BATT via a switching mechanism SW. Namely, the switching
mechanism SW enables the selection of a state where the motor MOT
and the generator GEN are electrically connected and a state where
the motor MOT and the battery BATT are electrically connected.
[0101] Hereinafter, embodiment of the rear wheel driving system 20,
which is a driving system by which the invention is characterized,
will be described in detail. Although the driving system by which
the invention is characterized may be used in the front wheel
driving system 10 of the wheeled vehicle V, here, the driving
system will be described as being used in the rear wheel driving
system 20.
First Embodiment
[0102] The rear wheel driving system 20 includes, as show in FIG.
2, the motor MOT and the power transmission mechanism TM2. Then,
the power transmission mechanism TM2 includes first and second
clutches CL1, CL2 which are provided on an output shaft 21 of the
motor MOY and two planetary gear mechanisms, which are first and
second planetary gear mechanism PL1, PL2. The first and second
planetary gear mechanisms PL1, PL2 are each made up of a so-called
single pinion planetary gear mechanism and include, respectively,
sun gears S1, S2, ring gears R1, R2, and carriers C1, C2 which
support pinions P1, P2 which mesh, respectively, with the sun gears
S1, S2 and the ring gears R1, R2 in such a way that the pinions P1,
P2 rotate on their own axes and revolve or walk around the sun
gears S1, S2. In the first embodiment and modified examples of the
first embodiment, the sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 make up first rotating elements
of first and second differential mechanisms. The carriers C1, C2 of
the first and second planetary gear mechanisms PL1, PL2 make up
second rotating elements of the first and second differential
mechanisms. The ring gears R1, R2 of the first and second planetary
gear mechanisms PL1, PL2 make up third rotating elements of the
first and second differential mechanisms. Then, the sun gear S1, S2
of the first and second planetary gear mechanisms PL1, PL2 are
connected to each other so as to rotate integrally via a connecting
shaft 23. The carriers C1, C2 of the first and second planetary
gear mechanisms PL1, PL2 are connected to the left and right rear
wheels LWr, RWr via joints J1, J2, respectively.
[0103] The first and second planetary gear mechanisms PL1, PL2 have
equal gear ratios and are disposed close to each other. The motor
MOT is disposed so as to be offset to the left in relation to an
axial direction relative to the first and second planetary gear
mechanisms PL1, PL2. In addition, the motor MOT overlaps the first
and second planetary gear mechanisms PL1, PL2 in a radial
direction.
[0104] A second input gear 33 is provided on the connecting shaft
23 that connects together the sun gears S1, S2 of the first and
second planetary gear mechanisms PL1, PL2 equidistantly from the
sun gears S1, S2 so as to rotate integrally with the sun gears S1,
S2. Then, this second input gear 33 meshes with a second output
gear 35 that is provided on the output shaft 21 of the motor
MOT.
[0105] The ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 have external teeth R1b, R2b that are formed on
outer circumferential surfaces thereof in addition to internal
teeth R1a, R2a that are formed on inner circumferential surfaces
thereof so as to mesh with the pinions P1, P2, respectively. The
external teeth R1b of the ring gear R1 of the first planetary gear
mechanism PL1 mesh with a first output gear 25 that is provided on
the output shaft 21 of the motor MOT. The external teeth R2b of the
ring gear R2 of the second planetary gear mechanism PL2 mesh with a
first input gear 29 that is provided coaxially with an idle gear 27
that meshes with the first output gear 25 so as to rotate
integrally. Namely, the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the external teeth
R1b of the ring gear R1 with the first output gear 25, the meshing
of the first output gear 25 with the idle gear 27, and the meshing
of the first input gear 29 with the external teeth R2b of the ring
gear R2. Reference Numeral 31 denotes an idle shaft to one end of
which the idle gear 27 is attached and to the other end of which
the first input gear 29 is attached.
[0106] The two ring gears R1, R2 operate so as to rotate in
opposite directions to each other as a result of the ring gears R1,
R2 of the first and second planetary gear mechanisms PL1, PL2 being
connected together through the odd number of times of meshing in
the way described above. Namely, a rotation of the ring gear R1 in
one direction causes the first output gear 25 to rotate in the
other direction through the meshing of the external teeth R1b of
the ring gear R1 with the first output gear 25. In addition, the
meshing of the first output gear 25 with the idle gear 27 causes
the idle gear 27 to rotate in one direction. Since the idle gear 27
and the first input gear 29 rotate integrally via the idle shaft
31, the first input gear 29 also rotates in the one direction.
Further, the rotation of the first input gear 29 in the one
direction acts to cause the ring gear R2 to rotate in the other
direction as a result of the first input gear 29 meshing with the
external teeth R2b of the ring gear R2.
[0107] Additionally, a gear ratio resulting from the meshing of the
external teeth R1b of the ring gear R1 with the first output gear
25 and a gear ratio resulting from the meshing of the first output
gear 25 with the idle gear 27 and the meshing of the first input
gear 29 with the external teeth R2b of the ring gear R2 are set so
that absolute values thereof become equal to each other.
Consequently, torque of the motor MOT that is transmitted to the
first output gear 25 is always transmitted to the ring gears R1, R2
as torque having the equal absolute value and acting in the
opposite directions.
[0108] A second output gear 35 provided on the output shaft 21 of
the motor MOT and the first output gear 25 are disposed so as not
only to rotate relatively but also to face each other in the axial
direction. The second output gear 35 and the first output gear 25
are made to rotate integrally with or rotate relative to the output
shaft 21 through switching by the first and second clutches CL1,
CL2. Namely, when applied or released, the first clutch CL1
connects or disconnects a power transmission between the output
shaft 21 of the motor MOT and the second output gear 35. When
applied or released, the second clutch CL2 connects or disconnects
a power transmission between the output shaft 21 of the motor MOT
and the first output gear 25. The first and second clutches CL1,
CL2 are each made up of a synchromesh mechanism that can be
switched over by a common actuator and can be switched over on the
same rotation axis, that is, the same rotation axis as the output
shaft 21 of the motor MOT.
[0109] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0110] In the state in which both the first and second clutches
CL1, CL2 are released, the output shaft 21 of the motor MOT is not
connected to either of the first output gear 25 and the second
output gear 35, whereby a power transmission path between the
output shaft 21 of the motor MOT and the first and second planetary
gear mechanisms PL1, PL2 becomes a disconnected state. When the
first and second clutches CL1, CL2 take the state in which the
clutches CL1, CL2 are both released, no torque is transmitted from
the motor MOT to the left and right rear wheels LWr, RWr, whereby
neither a left-right driving force sum nor a left-right driving
force difference is generated from the rear wheel driving system
20, this enabling a front-wheel drive (FWD), which will be
described later.
[0111] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the output shaft 21 of the
motor MOT is connected to the second output gear 35, whereby a
power transmission path between the output shaft 21 of the motor
MOT and the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state via a second input
gear 33. When the first and second clutches CL1, CL2 take the first
state, torques of the same magnitude are transmitted from the motor
MOT to the left and right rear wheels LWr, RWr in the same
direction in the front-rear direction, whereby a desired left-right
driving force sum is generated from the rear wheel driving system
20 while no left-right driving force difference is generated
therefrom, this enabling a four-wheel drive (4WD), which will be
described later.
[0112] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the output shaft
21 of the motor MOT is connected to the first output gear 25,
whereby a power transmission path between the output shaft 21 of
the motor MOT and the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 becomes a connected state. When
the first and second clutches CL1, CL2 take the second state,
torques of the same magnitude are transmitted from the motor MOT to
the left and right rear wheels LWr, RWr in opposite directions in
the front-rear direction, whereby a desired left-right driving
force difference is generated front the rear wheel driving system
20 while no left-right driving force sum is generated therefrom,
this enabling a torque vectoring drive (TV), which will be
described later.
[0113] Namely, the output shaft 21 of the motor MOT can selectively
be switched for connection with the sun gears S1, S2 of the first
and second planetary gear mechanisms PL1, PL2 and the ring gears
R1, R2 of the first and second planetary gear mechanisms PL1,
PL2.
[0114] In the rear wheel driving system 20 that is configured in
the way described heretofore, since the first and second planetary
gear mechanisms PL1, PL2 are configured in the way described above,
the sun gear S1, the carrier C1 and the ring gear R1 can transmit
power to one another, and rotation speeds thereof are in a
collinear relationship. Then, the sun gear S2, the carrier C2 and
the ring gear R2 can transmit power to one another, and rotation
speeds thereof are in a collinear relationship. Here, the collinear
relationship means a relationship in which the rotation speeds
thereof are aligned on a single straight line in a collinear
chart.
[0115] Since the sun gear S1 and the sun gear S2 are connected so
as to rotate integrally via the connecting shaft 23, the rotation
speeds of the sun gear S1 and the sun gear S2 are equal to each
other. Further, the two ring gears R1, R2 operate so as to rotate
in the opposite directions to each other at the same rotation speed
as a result of the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 being connected together through
the odd number of times of meshing. This means that to describe
using a collinear chart (for example, FIGS. 3A and 3B) showing
rotation speeds, the rotation speeds of the two ring gears R1, R2
are controlled under a relationship in which an imaginary line L1
that connects the two ring gears R1, R2 rotate on a point of
intersection where the imaginary line L1 intersects a zero rotation
line L2 as fulcrum O. In this embodiment, due to the gear rations
of the first and second planetary gear mechanisms PL1, PL2 being
equal, the point of intersection, which makes up the fulcrum,
between the imaginary line L1 and the zero rotation line L2 that
indicates zero rotation is positioned at a center of the zero
rotation line L2. However, in case the gear ratios of the first and
second planetary gear mechanisms PL1, PL2 differ, the point of
intersection takes a point on the zero rotation line L2 that
deviates from the center thereof.
[0116] Consequently, when the wheeled vehicle travels straight
ahead with no difference in rotation speed between the left and
right rear wheels LWr, RWr, the rotation speeds of the carriers C1,
C2 that are connected to the left and right rear wheels LWr, RWr
become equal to each other, and the imaginary line L1 that connects
the two ring gears R1, R2 coincides with the zero rotation line L2,
whereby the rotation speeds of the ring gears R1, R2 both become
zero rotation. On the other hand, when the wheeled vehicle turns
with a difference in rotation speed between the left and right rear
wheels LWr, RWr, a difference in rotation speed is generated on the
carriers C1, C2 that are connected to the left and right rear
wheels LWr, RWr, and the imaginary line L1 that connects the two
ring gears R1, R2 rotates about the fulcrum O, whereby the ring
gears R1, R2 rotate in the opposite directions at the same rotation
speed.
[0117] Hereinafter, the front-wheel drive (FWD), the four-wheel
drive (4WD) and the torque vectoring drive (TV) will be described
in detail.
--Front-Wheel Drive (FWD)--
[0118] When the state results in which both the first and second
clutches CL1, CL2 are released (the first clutch CL1: released/the
second clutch CL2: released), the power transmission path between
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state, and hence, no torque is
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr, whereby neither a left-right driving force sum nor a
left-right driving force difference is generated from the gear
wheel driving system 20. As shown in FIG. 3A, the imaginary line L1
coincides with the zero rotation line L2 when the wheeled vehicle
travels straight ahead with no difference in rotation speed between
the left and right rear wheels LWr, RWr, and the rotation speeds of
the ring gears R1, R2 become zero rotation. On the other hand, when
the wheeled vehicle turns with a difference in rotation speed
between the left and right rear wheels LWr, RWr, as shown in FIG.
3B, the imaginary line L1 rotates about the fulcrum O on the
collinear chart, and the ring gears R1, R2 rotate in the opposite
directions at the same rotation speed. In FIG. 3C, the rotating
elements of the power transmission mechanism TM2 are shown by solid
lines when the wheeled vehicle travels straight ahead by
front-wheel drive (FWD) with no difference in rotation speed
between the left and right rear wheels LWr, RWr (FIG. 3A). In FIG.
3D, the rotating elements of the power transmission mechanism TM2
are shown by solid lines when the wheeled vehicle turns by
front-wheel drive (FWD) with a difference in rotation speed between
the left and right rear wheels LWr, RWr (FIG. 3B).
--Four-Wheel Drive (4WD)--
[0119] When the first and second clutches CL1, CL2 are in the first
state (this first clutch CL1: applied/the second clutch CL2:
released), the power transmission path between the motor MOT and
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state by way of the second
output gear 35 and the second input gear 33, and motor torque M in
a forward direction is inputted from the motor MOT into the sun
gears S1, S2. In normal first and second planetary gear mechanisms
PL1, PL2, in the event that forward torque is inputted into sun
gears S1, S2, torque attempting to increase rotation speeds is
transmitted to carriers C1, C2 and ring rears R1, R2. However, in
the first and second planetary gear mechanisms PL1, PL2 of this
embodiment, as has been described above, the ring gears R1, R2 are
controlled so as to rotate only in the opposite directions to each
other at the same rotation speed, and therefore, with the ring
gears R1, R2 acting as fulcrums, the forward motor torque M that is
inputted into the sun gears S1, S2 that act as points of
application of force is transmitted to the carriers C1, C2 that act
as points of action as forward left and right rear wheel torques
T1, T2 that result from multiplying motor torques M1, M2 by the
gear ratios of the first and second planetary gear mechanisms PL1,
PL2. Since the gear ratios of the first and second planetary gear
mechanisms PL1, PL2 are equal, the left and right rear wheel
torques T1, T2 become torques having equal absolute values and
acting in the same direction, and this generates a left-right
driving force sum that corresponds to a sum of the left and right
rear wheel torques T1, T2 (T1+T2), whereby a forward driving force
is given to the wheeled vehicle V stably. A difference between the
left and right rear wheel torques T1, T2 (T1-T2) becomes zero, and
with the first and second clutch CL1, CL2 staying in the first
state, there is no such situation that a left-right driving force
difference is generated from the rear wheel driving system 20 due
to the generation of torque of the motor MOT, whereby no yaw moment
is given to the wheeled vehicle V. In this description, the forward
direction means a direction in which the wheeled vehicle V is
driven to travel forwards. The rotation direction of the motor MOT
that causes the wheeled vehicle V to travel forwards can be changed
depending on the arrangement of the gears and the number of gears.
In the case of giving torque in a reverse direction to the wheeled
vehicle V, namely, when the wheeled vehicle V is reversed, the
motor MOT should be torque controlled so as to generate torque
acting in an opposite direction to the direction in which the
torque acts when the wheeled vehicle V travels forwards.
[0120] In FIGS. 4A, 4B, arrows in a collinear chart indicate torque
acting on the individual elements, and an arrow reaching the
collinear chart from the motor MOT indicates a power transmission
path of the motor MOT (this will be the same also in FIG. 11). In
FIGS. 4C, 4D, the rotating elements of the power transmission
mechanism TM2 are indicated by solid lines when the vehicle V runs
by four-wheel drive (4WD).
[0121] When the vehicle V travels straight ahead with no difference
in rotation speed between the left and right rear wheels LWr, LWr,
as shown in FIG. 4A, the imaginary line L1 coincides with the zero
rotation line L2, whereby the rotation speeds of the ring gears R1,
R2 both become zero rotation. On the other hand, when the wheeled
vehicle V turns with a difference in rotation speed between the
left and right rear wheels LWr, RWr, as shown in FIG. 4B, the
imaginary line L1 rotates about the fulcrum O on the collinear
chart, and the ring gears R1, R2 rotate in the opposite directions
to each other at the same rotation speed. In FIG. 4c, the rotating
elements of the power transmission mechanism TM2 are shown by solid
lines when the wheeled vehicle V travels straight ahead by
four-wheel drive (4WD) with no difference in rotation speed between
the left and right rear wheels LWr, RWr (FIG. 4A). In FIG. 4D, the
rotating elements of the power transmission mechanism TM2 are shown
by solid lines when the wheeled vehicle V turns by four-wheel drive
(4WD) with a difference in rotation speed between the left and
right rear wheels LWr, RWr (FIG. 4B).
[0122] In this way, the desired front-rear driving force can be
generated in the left and right rear wheels LWr, RWr by controlling
the first and second clutches CL1, CL2 to be put in the first state
(the first clutch CL1: applied/the second clutch CL2: released) and
torque controlling the motor MOT by changing the rotation direction
of the motor MOT according to whether the vehicle V travels
forwards or rearwards, whereby a front-rear running assist can be
performed. This four-wheel drive (4WD) may be used as a starting
assist when the wheeled vehicle V starts from rest or may be
switched from the front wheel-drive (FWD) while the wheeled vehicle
is running. In switching from the front wheel-drive (FWD) to the
four-wheel drive (4WD) while the wheeled vehicle V is running, the
rotation speed of the motor MOT is increased to the same rotation
speed as that of the second output gear 35 with the first and
second clutches CL1, CL2 in FIG. 3 both left released, whereafter
the first clutch CL1 is applied, whereby the drive can be shifted
to the four-wheel drive (4WD) while suppressing the generation of
shift shock.
--Torque Vectoring Drive (TV)--
[0123] When the first and second clutches CL1, CL2 are in the
second state (the first clutch CL1: released/the second clutch CL2:
applied), the power transmission path between the motor MOT and the
ring gears R1, R2 of the first and second planetary gear mechanisms
PL1, PL2 becomes connected state, and motor torques having equal
absolute values and acting in opposite directions are inputted from
the motor MOT into the ring gears R1, R2.
[0124] Namely, the torque of the motor MOT gives a first motor
torque M1 that acts in a reverse direction opposite to the
direction of the torque of the motor MOT to the ring gear R1 as a
result of the external teeth R1b of the ring, gear R1 meshing with
the first output gear 25. As this occurs, the forward torque (not
shown) attempting to cause the wheeled vehicle V to travel forwards
is being applied to the carrier C1 from the left rear wheel LWr.
Thus, in the first planetary gear mechanism PL1, as a result of the
first motor torque M1 acting in the reverse direction being applied
to the ring gear R1 that acts as the point of application of force
with the carrier C1 acting as the fulcrum, a first motor torque
distribution forth M1' acting in the forward direction is applied
to the sun gears S1, S2 that act as the points of action.
[0125] Additionally, the torque of the motor MOT gives a second
motor torque M2 that acts in the forward direction that is the same
as the direction of the torque of the motor MOT to the ring gear R2
as a result of the first output gear 25 meshing with the idle gear
27 and the external teeth R2b of the ring gear R2 meshing with the
first input gear 29. As this occurs, the forward torque (not shown)
attempting to cause the wheeled vehicle V to travel forwards is
being applied to the carrier C2 from the right rear wheel RWr.
Thus, in the second planetary gear mechanism PL2, as a result of
the second motor torque M2 acting in the forward direction being
applied to the ring gear R2 that acts as the point of application
of force with the carrier C2 acting as the fulcrum, a second motor
torque distribution forth M2' acting in the reverse direction is
applied to the sun gears S1, S2 that act as the points of
action.
[0126] Here, the first motor torque M1 and the second motor torque
M2 are the torques having the equal absolute values and acting in
the opposite directions. Thus, the first motor torque distribution
force M1' acting in the forward direction and the second motor
torque distribution force M2' acting in the reverse direction to
the sun gears S1, S2 cancel (offset) each other. Due to this
offsetting of the first and second motor torque distribution forces
M1', M2', with the sun gear S1 acting as the fulcrum, the reverse
first motor torque M1 that is inputted into the ring gear R1 that
acts as the point of application of force is transmitted to the
carrier C1 that acts as the point of action as a reverse left rear
wheel torque T1 that results from being multiplied by the gear
ratio of the first planetary gear mechanism PL1. Then, with the sun
gear S2 acting as the fulcrum, the forward second motor torque M2
that is inputted into the ring gear R2 that acts as the point of
application of force is transmitted to the carrier C2 that acts as
the point of action as a forward right rear wheel torque T2 that
results from being multiplied by the gear ratio of the second
planetary gear mechanism PL2.
[0127] Since the gear ratios of the first and second planetary gear
mechanisms PL1, PL2 are equal, the left and right rear wheel
torques T1, T2 become torques having equal absolute values and
acting in opposite directions, and thus generates a left-right
driving force difference that corresponds to a difference between
the left and right rear wheel torques T1, T2 (T1-T2), whereby a
counterclockwise yaw moment Y is given to the wheeled vehicle V
stably. With the sum of the left and right rear wheel torques T1,
T2 (T1+T2) becomes zero and the first and second clutches CL1, CL2
staying in the second state, a left-right driving force sum is not
generated front the rear wheel driving system 20 by the generation
of torque of the motor MOT, and no front-rear torque is given to
the wheeled vehicle V. In the case of giving yaw moment acting in a
clockwise direction to the wheeled vehicle V, the motor MOT should
be torque controlled so as to generate torque acting in an opposite
direction to the direction described above.
[0128] In FIGS. 5A, 5B, arrows in a collinear chart indicate torque
acting on the individual elements, and an arrow reaching the
collinear chart from the motor MOT indicates a power transmission
path of the motor MOT (this will be the same also in FIG. 12). In
FIGS. 5C, 5D, the rotating elements of the power transmission
mechanism TM2 are indicated by solid lines when the wheeled vehicle
V runs by torque vectoring drive (TV).
[0129] When the wheeled vehicle V travels straight ahead with no
difference in rotation speed between the left and right rear wheels
LWr, RWr, as shown in FIG. 5A, the imaginary line L1 coincides with
the zero rotation line L2, whereby the rotation speeds of the ring
gears R1, R2 both become zero rotation. On the other hand, when the
wheeled vehicle V turns with a difference in rotation speed between
the left and right rear wheels LWr, RWr, as shown in FIG. 5B, the
imaginary line L1 rotates about the fulcrum O on the collinear
chart, and the ring gears R1, R2 rotate in the opposite directions
to each other at the same rotation speed. In FIG. 5c, the rotating
elements of the power transmission mechanism TM2 are shown by solid
lines when the wheeled vehicle V travels straight ahead by torque
vectoring drive (TV) with no difference in rotation speed between
the left and right rear wheels LWr, RWr (FIG. 5A). In FIG. 5D, the
rotating elements of the power transmission mechanism TM2 are shown
by solid lines when the wheeled vehicle V turns by torque vectoring
drive (TV) with a difference in rotation speed between the left and
right rear wheels LWr, RWr (FIG. 5B).
[0130] In this way, the desired yaw moment can be generated by
controlling the first and second clutches CL1, CL2 to be put in the
second state (the first clutch CL1: released/the second clutch CL2:
applied) and torque controlling the motor MOT by changing the
rotation direction of the motor MOT according to the turning
direction or lateral acceleration, whereby a turning assist can be
performed. In addition, the turning can be limited by generating a
yaw moment acting, in an opposite direction to the turning
direction.
[0131] In FIGS. 3B, 4B, 5B, left turn in which the rotation speed
of the right rear wheel RWr is faster than the relation speed of
the left rear wheel LWr is exemplified. However, right turn in
which the rotation speed of the left rear wheel LWr is faster than
the rotation speed of the right rear wheel RWr is similar to what
has been described in those figures (this will be true also in
FIGS. 10A, 11A, 12A).
[0132] FIG. 6 is a diagram showing flows of electric power when the
wheeled vehicle V travels by four-wheel drive (4WD) and torque
vectoring drive (TV).
[0133] When the wheeled vehicle V runs by four-wheel drive (4WD),
as an example, in such a state that the engine ENG is connected
with the generator GEN with the clutch CL applied (ON), the left
and right front wheels LWf, RWf are driven via the power
transmission mechanism TM1 by means of torque of the engine ENG,
and electricity is generated by the generator GEN by making use of
the torque of the engine ENG. Additionally, the motor MOT is
connected with the generator GEN via the switching mechanism SW,
and the motor MOT is driven by means of electric power generated in
the generator GEN. In this way, since large torque is needed when
the wheeled vehicle V starts from rest, the motor MOT is driven by
means of the electric power generated in the generator GEN that can
be connected with the engine ENG, thereby making it possible to
enhance the running performance of the wheeled vehicle V.
[0134] On the other hand, when the wheeled vehicle V runs by torque
vectoring drive (TV), as an example, in such a state that the
engine ENG is disconnected from the generator GEN by releasing the
clutch CL (OFF), the left and right front wheels LWf, RWf are
driven via the power transmission mechanism TM1 by the engine ENG,
and the motor MOT is connected with the battery BATT via the
switching mechanism SW, so that the motor MOT is driven by means of
electric power from the battery BATT. For example, when the wheeled
vehicle V is cruising at high speeds, the wheeled vehicle runs on
the torque of the engine ENG while running by torque vectoring
drive that requires not much torque using the electric power from
the battery BATT, thereby making it possible to enhance the energy
properties. The flows of electric power by torque vectoring drive
and 4WD drive are not limited to those shown in FIG. 6, and hence,
flows of electric power can be selected as required based on the
efficiency or the SOC of the battery BATT.
[0135] The front-wheel drive (FWD), four-wheel drive (4WD) and
torque vectoring drive (TV) can be switched over according to the
speed of the wheeled vehicle V (hereinafter, referred to as a
vehicle speed). The drive of the wheeled vehicle V may be switched
to four-wheel drive (4WD) in which the motor MOT is connected with
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 when the vehicle speed is slower than a
predetermined speed, and on the other hand, the drive of the
wheeled vehicle V may be switched to torque vectoring drive (TV) in
which the motor MOT is connected with the ring gears R1, R2 of the
first and second planetary gear mechanisms PL1, PL2 when the
vehicle speed is equal to or faster than the predetermined speed.
In addition, for example, the wheeled vehicle V may start from rest
by four-wheel drive (4WD) and may run by front-wheel drive (FWD) or
torque vectoring drive (TV) according to the vehicle speed and a
yaw moment request.
[0136] Thus, as has been described heretofore, the output shaft 21
of the motor MOT is connected to the sun gears S1, S2 of the first
and second planetary gear mechanisms PL1, PL2 and the ring gears
R1, R2 of the first and second planetary gear mechanisms PL1, PL2
so as to switch therebetween selectively. Thus, with the single
motor MOT, it becomes possible to output the front-rear torques
acting in the same direction to the left and right rear wheels LWr,
RWr or to output the torques acting in opposite directions to the
left rear wheel LWr and the right rear wheel RWr without generating
the front-rear torque. Further, the torque of the motor MOT is
inputted to the different rotating elements of the first and second
planetary gear mechanisms PL1, PL2 between when the front-rear
torques acting in the same direction are outputted to the left and
right rear wheels LWr, RWr and when the torques acting in the
opposite directions are outputted to the left rear wheel LWr and
the right rear wheel RWr without outputting the front-rear torque.
Thus, by changing the gear ratios of the sun gears S1, S2, the ring
gears R1, R2 and the carriers C1, C2, torque differences in
magnitude can be induced in the front-rear assist and the turning
assist.
[0137] Additionally, since the power transmission mechanism TM2 is
made up of the two first and second planetary gear mechanisms PL1,
PL2, a widthwise dimension can be reduced.
[0138] The power transmission mechanism TM2 includes the first and
second clutches CL1, CL2 and is configured to switch to the first
state and the second state selectively, and therefore, the power
transmission mechanism TM2 can transmit power to either of the sun
gears S1, S2 and the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 in an ensured fashion.
[0139] Additionally, the motor MOT is disposed on one side or a
left side of the first and second planetary gear mechanisms PL1,
PL2 in relation to the axial direction. Thus, compared with a case
where the motor MOT is disposed so as to be held by the first and
second planetary gear wheels PL1, PL2 therebetween, the joints J1,
J2 that make up connecting portions between the left and right rear
wheels LWr, RWr and the carriers CL1, CL2 can be disposed further
inwards in the vehicle's width direction, whereby angles from the
joints J1, J2 towards the left and right rear wheels LWr, RWr can
be restrained from being increased. This can enhance the degree of
freedom in relation to the lateral arrangement when mounting the
rear wheel driving system 20 on the wheeled vehicle V. It is noted
that the motor MOT may be disposed on the other side or a right
side of the first and second planetary gear mechanisms PL1,
PL2.
[0140] In addition, since the motor MOT overlaps the first and
second planetary gear mechanisms PL1, PL2 in a radial direction, a
radial dimension can also be reduced. This can enhance the degree
of freedom in relation to the front-rear mounting position on the
wheeled vehicle V in mounting the rear wheel driving system 20 on
the wheeled vehicle V.
[0141] The first and second clutches CL1, CL2 are the switching
mechanisms that are made up of the synchromesh mechanisms that can
be switched by the common actuator and can be switched on the same
rotation axis as the output shaft 21 of the motor MOT. Thus, it is
possible to avoid easily the risk of both the first and second
clutches CL1, CL2 being applied together, and compared with a case
where the first and second clutches CL1, CL2 are operable by
separate actuators, the number of components involved can be
reduced, thereby making it possible to suppress the production
costs. Further, the output shaft 21 of the motor MOT is also
disposed on the same axis as those of the first and second clutches
CL1, CL2 and therefore, the switching mechanisms can be disposed
while suppressing the radial dimension.
FIRST MODIFIED EXAMPLE
[0142] Following to the first embodiment, referring to FIG. 7, a
rear wheel driving system 20 of a first modified example thereof
will be described.
[0143] This first modified example is in common with the power
transmission mechanism TM2 of the first embodiment in that a power
transmission mechanism TM2 includes first and second clutches CL1,
CL2 and two planetary gear mechanisms of first and second planetary
gear mechanisms PL1, PL2. Thus, in the following description,
different features will mainly be described.
[0144] In a ring gear R1 of the first planetary gear mechanism PL1,
external teeth R1b mesh with a first input gear 42 that is provided
so as to rotate integrally with an idle shaft 41. In a ring gear R2
of the second planetary gear mechanism PL2, external teeth R2b mesh
with a second input gear 44 that meshes with an idle gear 43 that
is provided coaxially with the first input gear 42 so as to rotate
integrally. Namely, the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the external teeth
R1b of the ring gear R1 with the first input gear 42, the meshing
of the idle gear 43 with the second input gear 44, and the meshing
of the second input gear 44 with the external teeth R2b of the ring
gear R2.
[0145] The two ring gears R1, R2 operate so as to rotate in
opposite directions to each other as a result of the ring gears R1,
R2 of the first and second planetary gear mechanisms PL1, PL2 being
connected together through the odd number of times of meshing in
the way described above. Namely, a rotation of the ring gear R1 in
one direction causes the first input gear 42 to rotate in the other
direction through the meshing of the external teeth R1a of the ring
gear R1 with the first input shaft 42. Since the first input shaft
42 and the idle gear 43 rotate integrally via the idle shaft 41,
the idle gear 43 also rotates in the other direction. The second
input gear 44 rotates in the one direction as a result of the idle
gear 43 meshing with the second input gear 44. Further, as a result
of the second input gear 44 meshing with the external teeth R2b of
the ring gear R2, a rotation of the second input gear 44 in the one
direction acts so as to cause the ring gear R2 to rotate in the
other direction.
[0146] Additionally, a gear ratio resulting from the meshing of the
external teeth R1b of the ring gear R1 with the first input gear 42
and a gear ratio resulting from the meshing of the idle gear 43
with the second input gear 44 and the meshing of the second input
gear 44 with the external teeth R2b of the ring gear R2 are set so
that absolute values thereof become equal to each other.
Consequently, torque of a motor MOT is always transmitted to the
ring gears R1, R2 as torques having the equal absolute values and
acting in the opposite directions.
[0147] A hollow third input gear 46 is provided on a connecting
shaft 23 of the sun gears S1, S2 so as to surround an outer
circumference of the connecting shaft 23, and the hollow third
input gear 46 is configured to rotate integrally with or rotate
relatively to the connecting shaft 23 by being switched by the
first clutch CL1. Namely, the first clutch CL1 connects or
disconnects a power transmission between the third input gear 44
and the connecting shaft 23 by being applied or released. In
addition, a hollow first intermediate gear 47 is provided on an
outer circumferential side of the third input gear 46, and the
first intermediate gear 47 rotates together with or relative to the
third input gear 46 by being switched by the second clutch CL2.
Namely, the second clutch CL2 connects or disconnects a power
transmission between the third input gear 46 and the first
intermediate gear 47 by being applied or released. The first and
second clutches CL1, CL2 are each made up of a synchromesh
mechanism that can be switched over by a common actuator and can be
switched over on the same rotation axis, that is, the same rotation
axis as the sun gears S1, S2. The first intermediate shaft 47
meshes with a second intermediate gear 48 that is provided so as to
rotate integrally with the idle shaft 41.
[0148] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0149] In the state in which both the first and second clutches
CL1, CL2 are released, the third input gear 46 is connected with
neither the connecting shaft 23 nor the first intermediate gear 47,
whereby a power transmission path between the output shaft 21 of
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state. When the first and second
clutches CL1, CL2 take the state in which the clutches CL1, CL2 are
both released, no torque is transmitted from the motor MOT to the
left and right rear wheels LWr, RWr, whereby neither a left-right
driving force sum nor a left-right driving force difference is
generated from the rear wheel driving system 20, this enabling the
front-wheel drive (FWD).
[0150] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the third input gear 46 is
connected to the connecting shaft 23, whereby a power transmission
path between the output shaft 21 of the motor MOT and the sun gears
S1, S2 of the first and second planetary gear mechanisms PL1. PL2
becomes a connected state via an output gear 45 and the third input
gear 46. When the first and second clutches CL1, CL2 take the fast
state, torques of the same magnitude are transmitted from the motor
MOT to the left and right rear wheels LWr, RWr in the same
direction in the front-rear direction, therein a desired left-right
driving force sum is generated from the rear wheel driving system
20 while no left-right driving force difference is generated
therefrom, this enabling the four-wheel drive (4WD).
[0151] In the second in which the first clutch CL1 is released
while the second clutch CL2 is applied, the dual input gear 10 is
connected to the first intermediate gear 47, whereby a power
transmission path between the output shaft 21 of the motor MOT and
the ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state via the output gears
45, the third input gear 46, the first intermediate gear 47, the
second intermediate gear 48, the first input gear 42, the idle gear
43 and the second input gear 44. When the first and second clutches
CL1, CL2 take the second state, torques of the same magnitude are
transmitted from them motor MOT to the left and right rear wheels
LWr, RWr in opposite directions in the front-rear direction,
whereby a desired left-right driving force difference is generated
from the rear wheel driving system 20 while no left-right driving
force sum is generated therefrom, this enabling the torque
vectoring drive (TV). The front-wheel drive (FWD), the four-wheel
drive (4WD) and the torque vectoring drive (TV) are the same as
those of the first embodiment, and the detailed description thereof
will be omitted here.
[0152] According to the first modified example, the first and
second clutches CL1, CL2 are each made up of a synchromesh
mechanism that can be switched over by a common actuator and can be
switched over on the same rotation axis, that is, the same rotation
axis as those of the sun gears S1, S2. Thus, compared with a case
where the first and second clutches CL1, CL2 are operated by
separate actuators, the number of components involved can be
reduced, thereby making it possible to suppress the production
costs. Further, the first and second clutches CL1, CL2 can be
disposed by making effective use of the dead space defined between
the planetary gear mechanisms.
[0153] Further, in addition to the advantage of the first
embodiment, the torque of the motor MOT is transmitted to the ring
gears R1, R2 via the output gear 45 and the third input gear 46
even when the wheeled vehicle V runs by torque vectoring drive
(TV), thereby making it possible to secure a large gear ratio. In
addition, compared with the first embodiment, the number of
components that rotate integrally with the sun gears S1, S2 when
the wheeled vehicle V travels straight ahead by torque vectoring
drive (TV) is reduced. Therefore, not only can the inertial force
be reduced while the sun gears S1, S2 are rotating, but also a
scooping loss of lubricant can be reduced.
SECOND MODIFIED EXAMPLE
[0154] Following to the first modified example, referring to FIG.
8, a rear wheel driving system 20 of a second modified example of
the first embodiment will be described.
[0155] This modified example has the same configurations as those
of the first modified example except that a power transmission
mechanism TM2 has a third intermediate gear 50 that is provided
additionally on the idle shaft 41 of the power transmission
mechanism TM2 of the first modified example so as to rotate
relative to the idle shaft 41. Thus, like reference numerals will
be given to like constituent portions to those of the first
modified example so as to omit the description thereof, and only
different features will be described.
[0156] The third intermediate gear 50 always meshes with an output
gear 45 and a third input gear 46. Owing to this, in a first state
in which a first clutch CL1 is applied while a second clutch CL2 is
released, the third input gear 46 is connected to a connecting
shaft 23, whereby a power transmission path between an output shaft
21 of a motor MOT and sun gears S1, S2 of first and second
planetary gear mechanisms PL1, PL2 becomes a connected state via
the output gear 45, the third intermediate gear 50 and the third
input gear 46. On the other hand, in a second state in which the
first clutch CL1 is released while the second clutch CL2 is
applied, the third input gear 46 is connected to a first
intermediate gear 47, whereby a power transmission path between the
output shaft 21 of the motor MOT and ring gears R1, R2 of the first
and second planetary gear mechanisms PL1, PL2 becomes a connected
state via the output gear 45, the third middle gear 50, the third
input gear 46, the first intermediate gear 47, a second
intermediate gear 48, a first input gear 42, an idle gear 43 and a
second input gear 44.
[0157] Consequently, according to this modified example, in
addition to the advantage of the first modified example of the
first embodiment, the torque of the motor MOT is transmitted via
the third intermediate gear 50 even when the wheeled vehicle V runs
by four-wheel drive (4WD) or by torque vectoring drive (TV).
Therefore, a larger gear ratio can be ensured which becomes larger
by such an extent that the third intermediate gear 50 is added. It
should be noted that rotation directions of carriers C1, C2 become
opposite to those of the carriers C1, C2 of the first modified
example.
THIRD MODIFIED EXAMPLE
[0158] Next, referring to FIG. 9, a rear wheel driving system 20 of
a third modified example of the first embodiment will be
described.
[0159] The rear wheel driving system 20 includes, as shown in FIG.
9, a motor MOT and a power transmission mechanism TM2. Then, the
power transmission mechanism TM2 includes first and second clutches
CL1, CL2 which are provided on separate shafts and two planetary
gear mechanisms of first and second planetary gear mechanisms PL1,
PL2. The first and second planetary gear mechanisms PL1, PL2 are
each made up of a so-called single pinion planetary gear mechanism
and include, respectively, sun gears S1, S2, ring gears R1, R2 and
carriers C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring gears R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, the sun gears
S1, S2 of the first and second planetary gear mechanisms PL1, PL2
are connected to each other so as to rotate integrally via a
connecting shaft 23. The carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 are connected to the left and
right rear wheels LWr, RWr via joints J1, J2, respectively.
[0160] The first and second planetary gear mechanisms PL1, PL2 have
equal gear ratios and are disposed close to each other. The motor
MOT is disposed so as to be offset to the left in relation to an
axial direction relative to the first and second planetary gear
mechanisms PL1, PL2. In addition, the motor MOT overlaps the first
and second planetary gear mechanisms PL1, PL2 in a radial
direction.
[0161] The ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 have external teeth R1b, R2b that are formed on
outer circumferential surfaces thereof in addition to internal
teeth R1a , R2a that are formed on inner circumferential surfaces
thereof so as to mesh with the pinions P1, P2, respectively. The
external teeth R1b of the ring gear R1 of the first planetary gear
mechanism PL1 mesh with a first input gear 53 that is provided so
as to rotate integrally with an idle shaft 51. The external teeth
R2b of the ring gear R2 of the second planetary gear mechanism PL2
mesh with a first output gear 57 that meshs with an idle gear 55
that is provided coaxially with the first input gear 53 so as to
rotate integrally. Namely, the ring gears R1, R2 of the first and
second planetary gear mechanisms PL1, PL2 are connected together
through three times of meshing including the meshing of the
external teeth R1b of the ring gear R1 with the first input gear
53, the meshing of the idle gear 55 with the first output gear 57,
and the meshing of the first output gear 57 with the external teeth
R2b of the ring gear R2.
[0162] The two ring years R1, R2 operate so as to rotate in
opposite directions to each other as a result of the ring gears R1,
R2 of the first and second planetary gear mechanisms PL1, PL2 being
connected together through the odd number of times of meshing in
the way described above. Namely, a rotation of the ring gear R1 in
one direction causes the first input gear 53 to rotate in the other
direction through the meshing of the external teeth R1b of the ring
gear R1 with the first input shaft 53. Since the first input shaft
53 and the idle gear 55 rotate integrally via the idle shaft 51,
the idle gear 55 also rotates in the other direction. Additionally,
the first output gear 57 rotates in the other direction as a result
of the idle gear 55 meshing with the first output gear 57. Further,
as a result of the first output gear 57 with the external teeth R1b
of the ring gear R2, a rotation of the first output gear 57 in the
one direction acts so as to cause the ring gear R2 to rotate in the
other direction.
[0163] Additionally, a gear ratio resulting from the meshing of the
external teeth R1b of the ring gear R1 with the that input gear 53
and the meshing of the idle gear 55 with the first output gear 57
and a gear ratio resulting from the meshing of the first output
gear 57 with the external teeth R1b of the ring gear R1 are set so
that absolute values thereof become equal to each other.
Consequently, torque of a motor MOT is always transmitted to the
ring gears R1, R2 as torques having the equal absolute values and
acting in the opposite directions.
[0164] A hollow second input gear 59 is provided on the connecting
shaft 23 that connects the sun gears S1, S2 together so as to
surround an outer circumference of the connecting shaft 23, and the
hollow second input gear 59 is configured to rotate integrally with
or rotate relatively to the connecting shaft 23 by being switched
by the first clutch CL1. Namely, the first clutch CL1 connects or
disconnects a power transmission between the second input gear 59
and the connecting shaft 23 by being applied or released. This
second input gear 50 meshes with a second output gear 61 that is
provided do as to rotate internally with the output shaft 21 of the
motor MOT.
[0165] The second clutch CL2 is provided on the output shaft 21 of
the motor MOT in a position that overlaps the first clutch CL1 in
an axial direction. Then the first output gear 57 is configured so
as to rotate integrally with or relatively to the output shaft 21
through switching by second clutch CL2. Namely, the second clutch
connects or disconnects a power transmission between the output
shaft 21 of the motor MOT and the first output gear by being
applied or released.
[0166] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0167] In the state in which both the first and second clutches
CL1, CL2 are released, the output shaft 21 of the motor MOT is not
connected to the first output gear 57, and the second input gear is
also not brought into connection with the connecting shaft 23,
whereby a power transmission path between the output shaft 21 of
the motor MOT and the fist and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state. When the first and second
clutches CL1, CL2 take the state in which the clutches CL1, CL2 are
both released, no torque is transmitted from the motor MOT to the
left and right rear wheels LWr, RWr, wherein neither a left-right
driving force sum nor a left-right driving force difference is
generated from the gear wheel driving system 20, this enabling a
front-wheel drive (FWD), which will be described later.
[0168] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the second input gear is
connected to the connecting shaft 23, whereby a power transmission
path between the output shaft 21 of the motor MOT and the sun gears
S1, S2 of the first and second planetary gear mechanisms PL1, PL2
becomes a connected state via the second output gear 61 and the
second input gear 59. When the first and second clutches CL1, CL2
take the first state, torques of the same magnitude are transmitted
from the motor MOT to the left and right rear wheels LWr, RWr in
the same direction in the front-rear direction, whereby a desired
left-right driving force sum is generated from the rear wheel
driving system 20 while no left-right driving force difference is
generated therefrom, this enabling a four-wheel drive (4WD), which
will be described later.
[0169] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the output shaft
21 of the motor MOT is connected to the first output gear 57,
whereby a power transmission path between the output shaft 21 of
the motor MOT and the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 becomes a connected state via
the first output gear 57, the idle gear 55 and the first input gear
53. When the first and second clutches CL1, CL2 take the second
state, torques of the same magnitude are transmitted from the motor
MOT to the left and right wheels LWr, RWr in opposite directions in
the front-rear direction, whereby a desired left-right driving
force difference is generated from the rear wheel driving system 20
while no left-right driving force sum is generated therefrom, this
enabling a torque vectoring drive (TV), which will be described
later.
[0170] Namely, the output shaft 21 of the motor MOT can selectively
be switched for connection with the sun gears S1, S2 of the first
and second planetary gear mechanisms PL1, PL2 and the ring gears
R1, R2 of the first and second planetary gear mechanisms PL1, PL2.
With the rear wheel driving system 20 that is configured as
described above, too, the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
the odd number of times of meshing. Therefore, the rotation speeds
of the two ring gears R1, R2 are controlled under a relationship in
which an imaginary line L1 that connects the two ring gears R1, R2
rotate on a point of intersection where the imaginary line L1
intersects a zero rotation line L2 that indicates zero rotation as
a fulcrum O on a collinear chart.
[0171] Consequently, when the wheeled vehicle V travels straight
ahead with no difference in rotation speed between the left and
right rear wheels LWr, RWr, the rotation speeds of the carriers C1,
C2 that are connected to the left and right rear wheels LWr, RWr
become equal to each other, and the imaginary line L1 that connects
the two ring gears R1, R2 coincides with the zero rotation line L2,
whereby the rotation speeds of the ring gears R1, R2 both become
zero rotation. On the other hand when the wheeled vehicle V turns
with a difference in rotation speed between the left and right rear
wheels LWr, RWr, a difference in rotation speed is generated on the
carriers C1, C2 that are connected to the left and right rear
wheels LWr, RWr, and the imaginary line L1 that connects the two
ring gears R1, R2 rotates about the fulcrum O, whereby the ring
gears R1, R2 rotate in the opposite directions at the same rotation
speed.
[0172] Hereinafter, the front-wheel drive (FWD), the four-wheel
(4WD) and the torque vectoring drive (TV) will be described in
detail.
--Front-wheel Drive (FWD)--
[0173] When the state results in which both the first and second
clutches CL1, CL2 are released (the first clutch CL1: released/the
second clutch CL2: released), the power transmission path between
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state, and hence, no torque is
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr, whereby neither left-right driving force sum nor a
left-right driving force difference is generated from the rear
wheel driving system 20. When the wheeled vehicle V travels
straight ahead with no difference in rotation speed between the
left and right rear wheels LWr, RWr, as shown by solid lines in
FIG. 10A, the imaginary line L1 coincides with the zero rotation
line L2, whereby the rotation speeds of the ring gears R1, R2 both
become zero rotation. On the other hand, when the wheeled vehicle V
turns with a difference in rotation speed between the left and
right rear wheels LWr, RWr, as shown by broken lines in FIG. 10A,
the imaginary line L1 rotates about the fulcrum O on the collinear
chart, and the ring gears R1, R2 rotate in the opposite directions
to each other at the same rotation speed. In FIG. 10B, the rotating
elements of the power transmission mechanism TM2 are shown by solid
lines when the wheeled vehicle V travels straight ahead by
front-wheel drive (FWD) with no difference in rotation speed
between the left and right rear wheels LWr, RWr. Compared with the
straight ahead traveling by front-wheel drive (FWD) in the first
embodiment (FIG. 3C), since the second input gear 59 is
disconnected, in the power transmission mechanism TM2 of the third
modified example, the inertial force when the wheeled vehicle V
runs by front-wheel drive (FWD) can be reduced.
--Four-Wheel Drive (4WD)--
[0174] When the first and second clutches CL1, CL2 are in the first
state (the first clutch CL1: applied/the second clutch CL2:
released), the power transmission path between the motor MOT and
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state by way of the second
output gear 61 and the second input gear 59, and motor torque M in
a forward direction is inputted from the motor MOT into the sun
gears S1, S2. In normal first and second planetary gear mechanisms
PL1, PL2, in the event that forward torque is inputted into sun
gears S1, S2, torque attempting to increase rotation speeds is
transmitted to carriers C1, C2 and ring gears R1, R2. However, in
the first and second planetary gear mechanisms PL1, PL2 of this
embodiment, as has been described above, the ring gears R1, R2 are
controlled so as to rotate only in the opposite directions to each
other at the same rotation speed, and therefore, with the ring
gears R1, R2 acting as fulcrums, the forward motor torque M that is
inputted into the sun gears S1, S2 that act as points of
application of force is transmitted to the carriers C1, C2 that act
as points of action as forward left and right rear wheel torques
T1, T2 that result from multiplying motor torques M1, M2 by the
ratios of the first and second planetary gear mechanisms PL1, PL2.
Since the gear ratios of the first and second planetary gear
mechanisms PL1, PL2 are equal, the left and right gear wheel
torques T1, T2 become torques having equal absolute values and
acting in the same direction, and this generates a left-right
driving force sum that corresponds to a sum of the left and right
rear wheel torques T1, T2 (T1+T2), whereby a forward driving force
is given to the wheeled vehicle V stably. A difference between the
left and right rear wheel torques T1, T2 (T1-T2) becomes zero, and
with the first and second clutch CL1, CL2 staying in the first
state, there is no such situation that a left-right driving force
difference is generated from the rear wheel driving system 20 due
to the generation of torque of the motor MOT, whereby no yaw moment
is given to the wheeled vehicle V. In the case of giving torque in
a reverse direction to the wheeled vehicle V, namely, when the
wheeled vehicle V is reversed, the motor MOT should be torque
controlled so as to generate torque acting in an opposite direction
to the direction in which the torque acts when the wheeled vehicle
V travels forwards.
[0175] When the wheeled vehicle V travels straight ahead with no
difference in rotation speed between the left and right rear wheels
LWr, RWr, as shown by solid lines in FIG. 11A, the imaginary line
L1 coincides with the zero rotation line L1, whereby the rotation
speeds of the ring gears R1, R2 both become zero rotation. On the
other hand, when the wheeled vehicle V turns with a difference in
rotation speed between the left and right rear wheels LWr, RWr, as
shown by broken lines in FIG. 11A, the imaginary line L1 rotates
about the fulcrum O on the collinear chart, and the ring gears R1,
R2 rotate in the opposite directions to each other at the same
rotation speed. In FIG. 11B the rotating elements of the power
transmission mechanism TM2 with no difference in rotation speed
between the left and tight wheels LWr, RWr are shown by solid lines
when the wheeled vehicle V travels straight ahead by four-wheel
drive (4WD) with no difference in rotation speed between the left
and right rear wheels LWr, RWr.
[0176] In this way, the desired front-rear driving force can be
generated in the left and right rear wheels LWr, RWr by controlling
the first and second clutches CL1, CL2 to be put in the first state
(the first clutch CL1: applied/the second clutch CL2: released) and
torque controlling the motor MOT by changing the rotation direction
of the motor MOT according to whether the wheeled vehicle V travels
forwards or rearwards, whereby a front-rear running assist can be
performed. This four-wheel drive (4WD) may be used as a starting
assist when the wheeled vehicle V starts from rest or may be
switched from the front-wheel drive (FWD) while the wheeled vehicle
V is running. In switching from the front-wheel drive (FWD) to the
four-wheel drive (4WD) while the wheeled vehicle V is running, the
rotation speed of the motor MOT is increased to a rotation speed a
which a rotation speed of the second input gear 59 becomes the same
rotation speed as that of the connecting shaft 23 with the first
and second clutches CL1, CL2 in FIG. 10B both left released,
whereafter the first clutch CL1 is applied, whereby the drive can
be shifted to the four-wheel drive (4WD) while suppressing the
generation of shift shock.
--Torque Vectoring Drive (TV)--
[0177] As shown in FIG. 12A, when the first and second clutches
CL1, CL2 are in the second state (the first clutch CL1:
released/the second clutch CL2: applied), the power transmission
path between the motor MOT and the ring gears R1, R2 of the first
and second planetary gear mechanisms PL1, PL2 becomes a connected
state by way of the first output gear 57, the idle gear 55 and the
first input gear 53, and motor torques having equal absolute values
and acting in opposite directions are inputted from the motor MOT
into the ring gears R1, R2.
[0178] Namely, the torque of the motor MOT gives a first motor
torque M1 that acts in the reverse direction that is the same as
the direction of the torque of the motor MOT to the ring gear R1 as
a result of the first output gear 57 meshing with the idle gear 55
and the first input gear 53 meshing with the external teeth R1b of
the ring gear R1. As this occurs, the forward torque (not shown)
attempting to cause the wheeled vehicle V to travel forwards is
being applied to the carrier C1 from the left rear wheel LWr. Thus,
in the first planetary gear mechanism PL1, as a result of the first
motor torque M1 acting in the reverse direction being applied to
the ring gear R1 that acts as the point of application of force
with the carrier C1 acting as the fulcrum, a first motor torque
distribution forth M1' acting in the forward direction is applied
to the sun gears S1, S2 that act as the points of action.
[0179] Additionally, the torque of the motor MOT gives a second
motor torque M2 in a forward direction that is the same as the
direction of the torque of the motor MOT to the ring gear R2 as a
result of the first output gear 57 meshing with the external teeth
R2b of the ring gear R2. As this occurs, the forward torque (not
shown) attempting to cause the wheeled vehicle V to travel forwards
is being applied to the carrier C2 from the right rear wheel RWr.
Thus, in the second planetary gear mechanism PL2, as a result of
the second motor torque M2 acting in the forward direction being
applied to the ring gear R2 that acts as the point of application
of force with the carrier C2 acting as the fulcrum, a second motor
torque distribution forth M2' acting in the reverse direction is
applied to the sun gears S1, S2 that act as the points of
action.
[0180] Here, the first motor torque M1 and the second motor torque
M2 are the torques having the equal absolute values and acting in
the opposite directions. Thus, the first motor torque distribution
force M1' acting in the forward direction and the second motor
torque distribution force M2' acting in the reverse direction to
the sun gears S1, S2 cancel (offset) each other. Due to this
offsetting of the first and second motor torque distribution forces
M1', M2', with the sun gear S1 acting as the fulcrum, the reverse
first motor torque M1 that is inputted into the ring gear R1 that
acts as the point of application of force is transmitted to the
carrier C1 that acts as the point of action as a reverse left rear
wheel torque T1 that results from being multiplied by the gear
ratio of the first planetary gear mechanism PL1. Then, with the sun
gear S2 acting as the fulcrum, the forward second motor torque M2
that is inputted into the ring gear R2 that acts as the point of
application of force is transmitted to the carrier C2 that acts as
the point of action as a forward right rear wheel torque T2 that
results from being multiplied by the gear ratio of the second
planetary gear mechanism PL2.
[0181] Since the gear ratios of the first and second planetary gear
mechanisms PL1, PL2 are equal, the left and right rear wheel
torques T1, T2 become torques having equal absolute values and
acting in opposite directions, and this generates a left-right
driving force difference that corresponds to a difference between
the left and right rear wheel torques T1, T2 (T1-T2), whereby a
counterclockwise yaw moment Y is given to the wheeled vehicle V
stably. With the sum of the left and right rear wheel torques T1,
T2 (T1+T2) becomes zero and the first and second clutches CL1, CL2
staying in the second state, a left-right driving force sum is not
generated from the rear wheel driving system 20 by the generation
of torque of the motor MOT and no front-rear torque is given to the
wheeled vehicle V. In the case of giving yaw moment acting in a
clockwise direction to the wheeled vehicle V, the motor MOT should
be torque controlled so as to generate torque acting in an opposite
direction to the direction described above.
[0182] When the wheeled vehicle V travels straight ahead with no
difference in rotation speed between the left and right tear wheels
LWr, RWr, as shown by solid lines in FIG. 12A, the imaginary line
L1 coincides with the zero rotation line L2, whereby the rotation
speeds of the ring gears R1, R2 both become zero rotation. On the
other hand, when the wheeled vehicle V turns with a difference in
rotation speed between the left and right rear wheels LWr, RWr, as
shown by broken lines in FIG. 12A, the imaginary line L1 rotates
about the fulcrum O on the collinear chart, and the ring gears R1,
R2 rotate in the opposite directions to each other at the same
rotation speed. In FIG. 12B, the rotating elements of the power
transmission mechanism TM2 are shown by solid lines when the
wheeled vehicle V travels straight ahead by torque vectoring drive
(TV) with no difference in rotation speed between the left and
right rear wheels LWr, RWr by torque vectoring drive (TV).
[0183] In this way, the desired yaw moment can be generated by
controlling the first and second clutches CL1, CL2 to be put its
the second state (the first clutch CL1: released/the second clutch
CL2: applied) and torque controlling the motor MOT by changing the
rotation direction of the motor MOT according to the turning
direction or lateral acceleration, whereby a turning assist can be
performed. In addition, the turning can be limited by generating a
yaw moment acting in an opposite direction to the turning
direction.
[0184] Flows of electric power on the four-wheel drive (4WD) and
the torque vectoring drive (TV) are the same as those of the first
embodiment, and the description thereof will be omitted here. In
addition, the front-wheel drive (FWD), four-wheel drive (4WD) and
torque vectoring drive (TV) can be switched over according to the
vehicle speed as done in the first embodiment.
[0185] Thus, as has been described heretofore, the output shaft 21
of the motor MOT is connected to the sun gears S1, S2 of the first
and second planetary gear mechanisms PL1, PL2 and the ring gears
R1, R2 of the first and second planetary gear mechanisms PL1, PL2
so as to switch therebetween selectively. Thus, with the single
motor MOT, it becomes possible to output the front-rear torques
acting in the same direction to the left and right rear wheels LWr,
RWr or to output the torques acting in opposite directions to the
left rear wheel LWr and the right rear wheel RWr without generating
the front-rear torque. Further, the torque of the motor MOT is
inputted to the different rotating elements of the first and second
planetary gear mechanisms PL1, PL2 between when the front-rear
torques acting in the same direction are outputted to the left and
right rear wheels LWr, RWr and when the torques acting in the
opposite directions are outputted to the left rear wheel LWr and
the right rear wheel RWr without outputting the front-rear torque.
Thus, by changing the gear rations of the sun gears S1, S2, the
ring gears R1, R2 and the carriers C1, C2, torque differences in
magnitude can be induced in the front-rear assist and the turning
assist.
[0186] Additionally, since the power transmission mechanism TM2 is
made up of the two first and second planetary gear mechanisms PL1,
PL2, a widthwise dimension can be reduced.
[0187] The power transmission mechanism TM2 includes the first and
second clutches CL1, CL2 and is configured to switch to the first
state and the second state selectively, and therefore, the power
transmission mechanism TM2 can transmit power to either of the sun
gears S1, S2 and the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 in an ensured fashion.
[0188] Additionally, the motor MOT is disposed on one side or a
left side of the first and second planetary gear mechanisms PL1,
PL2 in relation to the axial direction. Thus, compared with a case
where the motor MOT is disposed so as to be held by the first and
second planetary gear wheels PL1, PL2 therebetween, the joints J1,
J2 that make up connecting portions between the left and right gear
wheels LWr, RWr and the carriers CL1, CL2 can be disposed further
inwards in the vehicle's width direction, whereby angles from the
joint J1, J2 towards the left and right rear wheels LWr, RWr can be
restrained from being increased. This can enhance the degree of
freedom in relation to the lateral arrangement when mounting the
rear wheel driving system 20 on the wheeled vehicle V. It is noted
that the motor MOT may be disposed on the other side or a right
side of the first and second planetary gear mechanisms PL1,
PL2.
[0189] In addition, since the motor MOT overlaps the first and
second planetary gear mechanisms PL1, PL2 in a radial direction, a
radial dimension can also be reduced. This can enhance the degree
of freedom in relation to the front-rear mounting position on the
wheeled vehicle V in mounting the rear wheel driving system 20 on
the wheeled vehicle V.
[0190] Additionally, the first clutch CL1 and the second clutch CL2
are disposed in positions that are offset in a radial direction and
are disposed in positions that overlap in an axial direction. This
can restrain an axial dimension of the power transmission
mechanisms TM2 from being increased. Further, the first and second
clutches CL1, CL2 may be configured so as to switch between the
first state and the second state by the use of a common
actuator.
[0191] In addition, since the first clutch CL1 is allowed 10 to
switch on the same rotation axis as those of the sun gears S1, S2,
the first and second clutches can he disposed by making effective
use of the dead space defined between the planetary gear
mechanisms.
[0192] In addition, compared with the first embodiment, the number
of components that rotate integrally with the sun gears S1, S2 when
the wheeled vehicle V travels straight ahead by torque vectoring
(TV) is reduced. Therefore, not only can the inertial force be
reduced while the sun gears S1, S2 are rotating, but also a
scooping loss of lubricant can be reduced.
FOURTH MODIFIED EXAMPLE
[0193] Following to the third modified example, referring to FIG.
13, a rear wheel driving system 20 of the fourth modified example
of the first embodiment will be described.
[0194] This modified example has the same configurations as those
of the power transmission TM2 of the third modified example except
that a second idle shaft 73 is provided additionally on the power
transmission mechanism TM2 of the third modified example and an
intermediate gear 75, a first output gear 57 and a second clutch
CL2 are provided on the second idle shaft 73. Thus, like reference
numerals will be given to like constituent portions to those of the
third modified example so as to omit the description thereof, and
only different features will be described.
[0195] The intermediate gear 75 is provided so as to rotate
integrally with the second idle shaft 73 and meshes with a second
output gear 61 and a second input gear 59 at all times. In
addition, the first output gear 57 is provided on the second idle
shaft 73, so as to rotate integrally with or relative to the second
idle shaft 73 through switching by the second clutch CL2. Owing to
this, in a first state in which a first clutch CL1 is applied while
the second clutch CL2 is released, the second input gear 59 is
connected to a connecting shaft 23, whereby a power transmission
path between an output shaft 21 of a motor MOT and sun gears S1, S2
of first and second planetary gear mechanisms PL1, PL2 becomes
connected state by way of the second output gear 61, the
intermediate gear 75 and the second input gear 59. On the other
hand, in a second state in which the first clutch CL1 is released
while the second clutch CL2 is applied, the first output gear 57 is
connected to the second idle shaft 73, whereby a power transmission
path between the output shaft 21 of the motor MOT and ring gears
R1, R2 of the first and second planetary gear mechanisms PL1, PL2
becomes a connected state by way of the second output gear 61, the
intermediate gear 75, the first output gear 57, the idle gear 55
and the first input gear 53.
[0196] Consequently, according to this modified example, in
addition to the advantage of the third modified example, the torque
of the motor MOT is transmitted via the intermediate gear 75 even
when the wheeled vehicle V runs by four-wheel drive (4WD) or by
torque vectoring drive (TV). Therefore, a larger gear ratio can be
ensured which becomes larger by such an extent that the
intermediate gear 75 is added. It should be noted that rotation
directions of carriers C1, C2 become opposite to those of the
carriers C1, C2 of the third modified example.
[0197] Further, according to this modified example, adding the
second idle shaft 73 can ensure a distance between the output shaft
21 of the motor MOT and the connecting shaft 23, and therefore,
even though the size of the motor MOT is enlarged, it is possible
to avoid the interference thereof with axles.
FIFTH MODIFIED EXAMPLE
[0198] Following to fourth modified example, referring to FIG. 14,
a rear wheel driving system 20 of a fifth modified example of the
first embodiment will be described.
[0199] In this modified example, a motor MOT is incorporated in a
power transmission mechanism TM2. The power transmission mechanism
TM2 includes the motor MOT, first and second clutches CL1, CL2 and
two planetary gear mechanisms of first and second planetary gear
mechanisms PL1, PL2. The first and second planetary gear mechanisms
PL1, PL2 are each made up of a so-called single pinion planetary
gear mechanism and include, respectively, sun gears S1, S2, ring
gears R1, R2 and carriers C1, C2 which support pinions P1, P2 which
mesh, respectively, with the sun gears S1, S2 and the ring gears
R1, R2 in such a way that the pinions P1, P2 rotate on their own
axes and revolve or walk around the sun gears S1, S2. Then, the sun
gears S1, S2 of the first and second planetary gear mechanisms PL1,
PL2 are connected to each other so as to rotate integrally via a
connecting shaft 23. The carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 are connected to left and right
rear wheels LWr, RWr via joints J1, J2, respectively.
[0200] The first and second planetary gear mechanisms PL1, PL2 have
equal gear ratios and are disposed so as to hold the motor MOT
therebetween.
[0201] In the ring gear R1 of the first planetary gear mechanism
PL1, external teeth R1b mesh with a first input gear 53 that is
provided so as to rotate integrally with an idle shaft 51. In the
ring gear R2 of the second planetary gear mechanism PL2, external
teeth R2b mesh with a second input gear 63 that meshes with an idle
gear 55 that is provided coaxially with the first input gear 53 so
as to rotate integrally. Namely, the ring gears R1, R2 of the first
and second planetary gear mechanisms PL1, PL2 are connected
together through three times of meshing including the meshing of
the external teeth R1b of the ring gear R1 with the first input
gear 53, the meshing of the idle gear 55 with the second input gear
63, and the meshing of the second input gear 63 with the external
teeth R1b of the ring gear R1.
[0202] The two ring gears R1, R2 operate so as to rotate in
opposite directions to each other as a result of the ring gears R1,
R2 of the first and second planetary gear mechanisms PL1, PL2 being
connected together through the odd number of times of meshing in
the way described above. Namely, a rotation of the ring gear R1 in
one direction causes the first input gear 53 to rotate in the other
direction through the meshing of the external teeth R1b of the ring
gear R1 with the first input shaft 53. Since the first input shaft
53 and the idle gear 55 rotate integrally via the idle shaft 55,
the idle gear 55 also rotates in the other direction. The second
input gear 63 rotates in the one direction as a result of the idle
gear 55 meshing with the second input gear 63. Further, as a result
of the second input gear 63 meshing with the external teeth R2b of
the ring gear R2, a rotation of the second input gear 63 in the one
direction acts so as to cause the ring gear R1 to rotate in the
other direction.
[0203] Additionally, a gear ratio resulting from the meshing of the
external teeth R1b of the ring gear R1 with the first input gear 53
and a gear ratio resulting from the meshing of the idle near 55
with the second input gear 63 and the meshing of the second input
gear 63 with the external teeth R2b of the ring gear R2 are set so
that absolute values thereof become equal to each other.
Consequently, torque of a motor MOT is always transmitted to the
ring gears R1, R2 as torques having the equal absolute values and
acting in the opposite directions.
[0204] A hollow third input gear 65 is provided on a connecting
shaft 23 that connects together the sun gears S1, S2 so as to
surround an outer circumference of the connecting shaft 23, and the
hollow third input gear 65 is configured to rotate integrally with
or rotate relatively to the connecting shaft 23 through switching
by the first clutch CL1. Namely, the first clutch CL1 connects or
disconnects a power transmission between the third input gear 65
and the connecting shaft 23 by being applied or released.
[0205] In addition, the motor MOT is provided between the third
input gear 65 and the sun gear S1 so as to surround the outer
circumference of the connecting ring shaft 23, and a hollow output
shaft 21 of the motor MOT is provided so as to extend towards a
third input gear 65 so as to rotate relative to the connecting
shaft 23.
[0206] A second output gear 61 is provided on the output shaft 21
of the motor MOT so as to rotate integrally with the output shaft
21, and the second output gear 61 meshes with a fourth input gear
69 that is provided so as to rotate integrally with or rotate
relatively to the idle shaft 51 through switching by the second
clutch CL2. A second output gear 67 is provided on the fourth input
gear 69 so as to rotate integrally with the fourth input gear 69,
and the second output gear 67 meshes with the third input gear 65
that is provided on the connecting shaft 23. Namely, the second
clutch CL2 connects or disconnects a power transmission between the
idle shaft 51 and the fourth input gear 69 and the second output
shall 67 by being applied or released.
[0207] The first and second clutches CL1, CL2 are allowed to the
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0208] In the state in which both the first and second clutches
CL1, CL2 are released, the fourth input gear 69 and the second
output gear 67 are not connected to the idle shaft 51 and the third
input gear 65 is not connected to the connecting shaft 23, either,
whereby a power transmission path between the output shaft 21 of
the motor MOT and the first and second planetary gear mechanism
PL1, PL2 becomes a disconnected state. When the first and second
clutches CL1, CL2 take the state in which the clutches CL1, CL2 are
both released, no torque is transmitted from the motor MOT to the
left and right rear wheels LWr, RWr, whereby neither a left-right
driving force sum nor a left-right driving force difference is
generated from the rear wheel driving system 20, this enabling a
front-wheel drive (FWD).
[0209] In the first state in which a first clutch CL1 is applied
while the second clutch CL2 is released, the third input gear 65 is
connected to the connecting shaft 23, whereby the power
transmission path between the output shaft 21 of the motor MOT and
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state by way of the second
output gear 61, the fourth input gear 69 the second output gear 47
and the third input gear 65. When the first and second clutches
CL1, CL2 take the first state, torques of the same magnitude are
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr in the same direction in the front-rear direction, whereby
a desired left-right driving force sum is generated from the rear
wheel driving system 20 while no left-right driving force
difference is generated therefrom, this enabling a four-wheel drive
(4WD).
[0210] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the fourth input
gear 69 and the second output gear 67 are connected to the idle
shaft 51, whereby a power transmission path between the output
shaft 21 of the motor MOT and the ring gears R1, R2 of the first
and second planetary gear mechanisms PL1, PL2 becomes a connected
state by way of the second output gear 61, the fourth input gear 69
(the second output gear 67), the first input gear 53, the idle gear
55 and the second input gear 63. When the first and second clutches
CL1, CL2 take the second state, torques of the same magnitude are
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr in opposite directions in the front-rear direction,
whereby a desired left-right driving force difference is generated
from the rear wheel driving system 20 while no left-right driving
force sum is generated therefrom, this enabling a torque vectoring
drive (TV). The front-wheel drive (FWD), the four-wheel drive (4WD)
and the torque vectoring drive (TV) are the same as those of the
third modified example, and the detailed description thereof will
be omitted here.
[0211] According to this modified example, since the motor MOT is
disposed on the same rotation axis as those of the sun gears S1,
S2, a radial dimension can be reduced.
[0212] In addition to the advantage of the third modified example,
the torque of the motor MOT is transmitted to the ring gears R1, R2
via the second output gear 61 and the fourth input gear 69 even
when the wheeled vehicle V runs by torque vectoring drive (TV),
thereby making it possible to secure a large gear ratio.
Second Embodiment
[0213] Next, referring to FIG. 15A, a rear wheel driving system 20
of a second embodiment will be described.
[0214] In this embodiment, a power transmission mechanism TM2
includes first and second clutches CL1, CL2 and two planetary gear
mechanisms, which are first and second planetary gear mechanisms
PL1, PL2. The first and second planetary gear mechanisms PL1, PL2
are each made up of a so-called single pinion planetary gear
mechanism and include, respectively, sun gears S1, S2, ring gears
R1, R2 and carriers C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring gears R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, in this
embodiment, the ring gears R1, R2 of the first and second planetary
gear mechanisms PL1, PL2 make up first rotating elements of first
and second differential mechanisms, the carriers C1, C2 of the
first and second planetary gear mechanisms PL1, PL2 make up second
rotating elements of the first and second differential mechanisms,
and the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 make up third rotating elements of the first
and second differential mechanisms. The ring gears R1, R2 of the
first and second planetary gear mechanisms PL1, PL2 are connected
to each other so as to rotate integrally. The carriers C1, C2 of
the first and second planetary gear mechanisms PL1, PL2 are
connected to left and right rear wheels LWr, RWr via joints J1, J2
respectively.
[0215] In the sun gear S1 of the first planetary gear mechanism
PL1, large-diameter external teeth S1b that are formed integrally
with small-diameter external teeth S1a that are formed on an outer
circumferential surface thereof so as to mesh with the pinions P1
meshes with an idle gear 83 that meshes with a first output gear 81
that is provided so as to rotate integrally with an output shaft
21. In the sun gear S2 of the second planetary gear mechanism PL2,
large-diameter external teeth S2b that are formed integrally with
small-diameter external teeth S2a that are formed on an outer
circumferential surface thereof so as to mesh with the pinions P2
meshes with a hollow second output gear 85 that covers an outer
circumference of the output shaft 21 of a motor MOT. The second
output gear 85 is provided on the output shaft 21 of the motor MOT
so as to rotate relatively thereto and is configured so as to
rotate integrally with or relative to the output shaft 21 through
switching by the second clutch CL2.
[0216] Namely, the sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the large-diameter
external teeth S1b with the idle gear 83, the meshing of the idle
gear 83 with the first output gear 81, and the meshing of the
second output gear 85 with the large-diameter external teeth S2b of
the sun gear S2. The two sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 operate so as to rotate in
opposite directions to each other as a result of the sun gears S1,
S2 being connected together through the odd number of times of
meshing in the way described above.
[0217] Additionally, a gear ratio resulting from the meshing of the
large-diameter external teeth S1b of the sun gear S1 with the idle
gear 83 and the meshing of the idle gear 83 with the first output
gear 81 and a gear ratio resulting from the meshing of the
large-diameter external teeth S2b of the sun gear S2 with the
second output gear 85 are set so that absolute values thereof
become equal to each other. Consequently, the torque of the motor
MOT is always transmitted to the sun gears S1, S2 as torques having
the equal absolute values and acting in the opposite
directions.
[0218] The ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 have common external teeth R1b (R2b) that are
formed on outer circumferential surfaces thereof in addition to
internal teeth R1a, R2a that are formed on inner circumferential
surface thereof so as to mesh with the pinions P1, P2.
[0219] A hollow third output gear 87 is provided on the output
shaft 21 of the motor MOT so as to surround an outer circumference
of the output shaft 21, and the third output gear 87 meshes with
the external teeth R1b (R2b) of the ring gears R1, R2 that are
formed integrally of the first and second planetary gear mechanisms
PL1, PL2. The third output gear 87 is configured so as to rotate
integrally with or relative to the output shaft 21 through
switching by the first clutch CL1. Namely, the first clutch CL1
connects or disconnects a power transmission between the third
output gear 87 and the output shaft 21 by being applied or
released. In addition, the second clutch CL1 connects or
disconnects a power transmission between the second output gear 85
and the output shaft 21 by being applied or released. The first and
second clutches CL1, CL2 are each made up of a synchromesh
mechanism that can be switched over by a common actuator and can be
switched over on the same rotation axis, that is, the same rotation
axis as the output shaft 21.
[0220] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0221] In the state in which both the first and second clutches
CL1, CL2 are released, the output shaft 21 is not brought into
connection with either of the second output gear 85 and the third
output gear 87, whereby a power transmission path between the
output shaft 21 of the motor MOT and the first and second planetary
gear mechanims PL1, PL2 becomes disconnected state. When the first
and second clutches CL1, CL2 take the state in which the clutches
CL1, CL2 are both released, no torque is transmitted from the motor
MOT to the left and right rear wheels LWr, RWr, whereby neither a
left-right driving force sum nor a left-right driving force
difference is generated from the rear wheel driving system 20, this
enabling a front-wheel drive (FWD).
[0222] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the output shaft 21 is
connected to the third output gear 87, whereby a power transmission
path between the output shaft 21 of the motor MOT and the ring
gears R2, R2 of the first and second planetary gear mechanisms PL1,
PL2 becomes a connected state. When the first and second clutches
CL1, CL2 take the first state torques of the same magnitude are
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr in the same direction in the front-rear direction, whereby
a desired left-right driving force sum is generated from the rear
wheel driving system 20 while no left-right driving force
difference is generated therefrom, this enabling a four-wheel drive
(4WD).
[0223] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the second output
gear 85 is connected to the output shaft 21 of the motor MOT,
whereby a power transmission path between the output shaft 21 and
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state. When the first and
second clutches CL1, CL2 take the second state, torques of the same
magnitude are transmitted from the motor MOT to the left and right
rear wheels LWr, RWr in opposite directions in the front-rear
direction, whereby a desired left-right driving force difference is
generated front the rear wheel driving system 20 while no
left-right driving force sum is generated therefrom, this enabling
a torque vectoring drive (TV).
[0224] In the rear wheel driving system 20 that is configured in
the way described heretofore, since the first and second planetary
gear mechanisms PL1, PL2 are configured in the way described above,
the sun gear S1, the carrier C1 and the ring gear R1 can transmit
power to one another, and rotation speeds thereof are in a
collinear relationship. Then, the sun gear S2, the carrier C2 and
the ring gear R2 can transmit power to one another, and rotation
speeds thereof are in a collinear relationship.
[0225] Since the ring gear R1 and the ring gear R2 are connected so
as to rotate integrally rotation speeds of the ring gear R1 and the
ring gear R2 become equal to each other. The two sun gears S1, S2
of the first and second planetary gear mechanisms PL1, PL2 operate
so as to rotate in opposite directions to each other at the same
rotation speed as a result of the sun gears S1, S2 being corrected
together through the odd no number of times of meshing. This means
that to describe using a collinear chart in FIG. 15B, the rotation
speeds of the two sun gears S1, S2 are controlled under a
relationship in which an imaginary line L1 that connects the two
sun gears S1, S2 rotate on a point of intersection where the
imaginary line L1 intersects a zero rotation line L2 as a fulcrum
O.
[0226] FIG. 15B(a) is a collinear chart of when the rear wheel
driving system 20 of the second embodiment operates in such a way
that the wheeled vehicle V travels straight ahead by front-wheel
drive (FWD). FIG. 15B(b) is a collinear chart of when the rear
wheel driving system 20 of the second embodiment operates in such a
way that the wheeled vehicle V travels straight ahead by four-wheel
drove (4WD), and arrows in the collinear chart indicate torques
acting on the elements. FIG. 15B(c) is a collinear chart of when
the rear wheel driving system 20 of the second embodiment operates
in such a way that the wheeled vehicle V travels straight ahead by
torque vectoring drive (TV), and arrows in the collinear chart
indicate torque acting on the elements. In this embodiment and
embodiments that will be described later, the illustration of
collinear charts of when the wheeled vehicle V turns with a
difference in rotation speed between the left and right rear wheels
LWr, RWr will be omitted.
[0227] As shown in FIG. 15B(a), when the wheeled vehicle V is
running by front-wheel drive (FWD) with both the first and second
clutches CL1, CL2 left released, a power transmission path between
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state, and hence, no torque is
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr, whereby neither a left-right driving force sum nor a
left-right driving force difference is generated from the rear
wheel driving system 20.
[0228] As shown in FIG. 15B(b), when the wheeled vehicle V is
running by four-wheel drive (4WD) with the first and second
clutches CL1, CL2 put in the first state, a power transmission path
between the motor MOT and the ring gears R1, R2 of the first and
second planetary gear mechanisms PL1, PL2 becomes a connected state
via the third output gear 87, whereby forward motor torque M is
inputted from the motor MOT into the ring gears R1, R2. In normal
first and second planetary gear mechanisms PL1, PL2, in the event
that forward torque is inputted into ring gears R1, R2, torque
attempting to increase rotation speeds is transmitted to sun gears
S1, S2 and carriers C1, C2. However, in the first and second
planetary gear mechanisms PL1, PL2 of this embodiment, as has been
described above, the sun gears S1, S2 are controlled so as to
rotate only in the opposite directions to each other at the same
rotation speed, and therefore, with the sun gears S1, S2 acting as
fulcrums, the forward motor torque M that is inputted into the ring
gears R1, R2 that act as points of application of force is
transmitted to the carriers C1, C2 that act as points of action as
forward left and right rear wheel torques T1, T2 that result front
multiplying motor torques M1, M2 by the gear ratios of the first
and second planetary gear mechanisms PL1, PL2. Since the gear
ratios of the first and second planetary gear mechanisms PL1, PL2
are equal, the left and right rear wheel torques T1, T2 become
torques having equal absolute values and acting in the same
direction, and this generates a left-right driving force sum that
corresponds to a sum of the left and right rear wheel torques T1,
T2 (T1+T2), whereby a forward driving force is given to the wheeled
vehicle V stably. A difference between the left and right rear
wheel torques T1, T2 (T1-T2) becomes zero, and with the first and
second clutch CL1, CL2 staying in the first state, there is no such
situation that a left-right driving force difference is generated
from the rear wheel driving system 20 due to the generation of
torque of the motor MOT, whereby no yaw moment is given to the
wheeled vehicle V.
[0229] As shown in FIG. 15B(c), when the wheeled vehicle V is
running by torque vectoring drive (TV) with the first and second
clutches CL1, CL2 put in the second state, a power transmission
path between the motor MOT and the sun gears S1, S2 of the first
and second planetary gear mechanisms PL1, PL2 becomes a connected
state, whereby the motor torques M1, M2 having equal absolute
values and acting in the opposite directions are inputted from the
motor MOT into the sun gears S1, S2. Since in the ring gears R1, R2
motor torque distribution forces cancel (offset) each other, the
left and right rear wheel torques T1, T2 having equal absolute
values and acting in the opposite directions are generated in the
carriers C1, C2, whereby a left-right driving force difference
corresponding a difference (T1-T2) between the left and right rear
wheels torques T1, T2 is generated, and a counterclockwise yaw
moment Y is given to the wheeled vehicle V in a stable fashion.
With the sum of the left and right rear wheel torques T1, T2
(T1+T2) becomes zero and the first and second clutches CL1, CL2
staying in the second state, a left-right driving force sum is not
generated from the rear wheel driving system 20 by the generation
of torque of the motor MOT, and no front-rear torque is given to
the wheeled vehicle V.
[0230] Thus, with this embodiment, too, as has been described
heretofore, the output shaft 21 of the motor MOT is connected to
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 and the ring gears R1, R2 of the first and
second planetary gear mechanisms PL1, PL2 so as to switch
therebetween selectively. Thus, with the single motor MOT, it
becomes possible to output the front-rear torques acting in the
same direction to the left and right rear wheels LWr, RWr or to
output the torques acting in opposite directions to the left rear
wheel LWr and the right rear wheel RWr without generating the
front-rear torque. Further, the torque of the motor MOT is inputted
to the different totaling elements of the host and second planetary
gear mechanisms PL1, PL2 between when the front-rear torques acting
in the same direction are outputted to the left and right rear
wheels LWr, RWr and when the torques acting in the opposite
directions are outputted to the left rear wheel LWr and the right
rear wheel RWr without outputting the front-rear torque. Thus, by
changing the gear ratios of the sun gears S1, S2, the ring gears
R1, R2 and the carriers C1, C2, torque differences in magnitude can
be induced in the front-rear assist and the turning assist.
Third Embodiment
[0231] Next, referring to FIG. 16A, a rear wheel driving system 20
of a third embodiment will be described.
[0232] In this embodiment, a power transmission mechanism TM2
includes first and second clutches CL1, CL2 and two planetary gear
mechanisms, which are first and second planetary gear mechanisms
PL1, PL2. The first and second planetary gear mechanisms PL1, PL2
are each made up of a so-called single pinion planetary gear
mechanism and include, respectively, sun gears S1, S2, ring gears
R1, R2 and carries C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring gears R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, in this
embodiment, the carriers C1, C2 of the first and second planetary
gear mechanisms PL1, PL2 make up first rotating elements of first
and second differential mechanisms, the sun gears S1, S2 of the
first and second planetary gear mechanisms PL1, PL2 make up second
rotating elements of the first and second differential mechanisms,
and the ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 make up third rotating elements of the first
and second differential mechanisms. The carriers C1, C2 of the
first and second planetary gear mechanisms PL1, PL2 are connected
to each other so as to rotate integrally and have a common second
input gear 89. This second input gear 89 meshes with a hollow
second output gear 35 that surrounds an outer circumference of an
output shaft 21 of a motor MOT. The second output gear 33 is
provided on the output shaft 21 of the motor MOT so as to rotate
relatively thereto and is configured so as to rotate integrally
with or relative to the output shaft 21 through switching by the
first clutch CL1. In addition, the sun gears S1, S2 are connected
to the left and right rear wheels LWr, RWr via joints J1, J2,
respectively.
[0233] In the ring gear R1 of the first planetary gear mechanism
PL, external teeth R1b that are formed integrally with internal
teeth R1a that are formed on an inner circumferential surface so as
to mesh with the pinions P1 meshes with a hollow first output gear
23 that surrounds an outer circumference of the output shaft 21 of
the motor MOT. In the ring gear R2 of the second planetary gear
mechanism PL2, external teeth R2b that are formed integrally with
internal teeth R2a that are formed on an inner circumferential
surface so as to mesh with the pinions P2 meshes with a first input
gear 29 that is provided on an idle shaft 31 of an idle gear 27
that meshes with the first output gear 25 so as to rotate
integrally.
[0234] Namely, the ring gears R1, R2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the external teeth
R1b of the ring gear R1 with the first output gear 25, the meshing
of the first output gear 25 with the idle gear 27, and the meshing
of the first input gear 29 with the external teeth R2b of the ring
gear R2. The two ring gears R1, R2 operate so as to rotate in
opposite directions to each other as a result of the ring gears R1,
R2 of the first and second planetary gear mechanisms PL1, PL2 being
connected together through the odd number of times of meshing in
the way described above.
[0235] Additionally, a gear ratio resulting from the meshing of the
external teeth R1b of the ring gear R1 with the first output gear
25 and a gear ratio resulting from the meshing of the first output
gear 25 with the idle gear 27 and the meshing of the first input
gear 29 with the external teeth R2b of the ring gear R2 are set so
that absolute values thereof become equal to each other.
Consequently, torque of a motor MOT is always transmitted to the
ring gears R1, R2 as torques having the equal absolute values and
acting in the opposite directions.
[0236] A second output gear 35 provided on the output shaft 21 of
the motor MOT and the first output gear 25 are disposed so as not
only to rotate relatively but also to face each other in the axial
direction. The second output gear 35 and the first output gear 25
are made to rotate integrally with or rotate relatively to the
output shaft 21 through switching by the first and second clutches
CL1, CL2. Namely, when applied or released, the first clutch CL1
connects or disconnects a power transmission between the output
shaft 21 of the motor MOT and the second output gear 35. When
applied or released, the second clutch CL2 connects or disconnects
a power transmission between the output shaft 21 of the motor MOT
and the first output gear 25. The first and second clutches CL1,
CL2 are each made up of a synchromesh mechanism that can be
switched over by a common actuator and can be switched over on the
same rotation axis, that is the same rotation axis as the output
shaft 21 of the motor MOT.
[0237] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0238] In the state in which both the first and second clutches
CL1, CL2 are released, the first output gear 25 and the second
input gear 35 are not brought into connection with the output shaft
21, whereby a power transmission path between the output shaft 21
of the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state. When the first and second
CL1, CL2 take the state in which the clutches CL1, CL2 are both
released, no torque is transmitted from the motor MOT to the left
and right rear wheels LWr, RWr, whereby neither a left-right
driving force sum nor a left-right driving force difference is
generated front the rear wheel driving system 20, this enabling a
front-wheel drive (FWD).
[0239] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the second output gear is
connected to the output shaft 21 of the motor MOT, whereby a power
transmission path between the output shaft 21 and the carriers C1,
C2 of the first and second planetary gear mechanisms PL1, PL2
becomes a connected state. When the first and second clutches CL1,
CL2 take the first state, torques of the same magnitude are
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr in the same direction in the front-rear direction, whereby
a desired left-right driving force sum is generated from the rear
wheel driving system 20 while no left-right driving force
difference is generated therefrom, this enabling a four-wheel drive
(4WD).
[0240] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the first output
gear 25 connected to the output shaft 21 of the motor MOT, whereby
a power transmission path between the output shaft 21 and the ring
gears R1, R2 of the first and second planetary gear mechanisms PL1,
PL2 becomes a connected state via the first output gear 25, the
idle gear 27 and the first input gear 29. When the first and second
clutches CL1, CL2 take the second gate torques of the same
magnitude are transmitted from the motor MOT to the left and right
rear wheels LWr, RWr in opposite directions in the front-rear
direction, whereby a desired left-right driving force difference is
generated from the rear wheel driving system 20 while no left-right
driving force sum is generated therefrom, this enabling a torque
vectoring drive (TV).
[0241] In the rear wheel driving system 20 that is configured in
the way described heretofore, since the first and second planetary
gear mechanisms PL1, PL2 are configured in the way described above,
the sun gear S1, the carrier C1 and the ring gear R1 can transmit
power to one another, and rotation speeds thereof are in a
collinear relationship. Then, the sun gear S2 the carrier C1 and
the ring gear R2 can transmit power to one another, and rotation
speeds thereof are in a collinear relationship.
[0242] Additionally, since the carrier C1 and the carrier C2 are
connected so as to rotate integrally, rotation speeds of the
carrier C1 and the carrier C2 become equal to each other. Further,
the two ring gears R1, R2 operate so as to rotate in the opposite
directions to each other at the same rotation speed as a result of
the ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 being connected together through the odd number
of times of meshing. This means that to describe using a collinear
chart in FIG. 16B, the rotation speeds of the two ring gears R1, R2
are controlled under a relationship in which an imaginary line L1
that connects the two ring gears R1, R2 rotate on a point of
intersection where the imaginary line L1 intersects a zero rotation
line L2 as a fulcrum O.
[0243] FIG. 16B(a) is a collinear chart of when the rear wheel
driving system 20 of the third embodiment operates in such a way
that the wheeled vehicle V travels straight ahead by front-wheel
drive (FWD). FIG. 16B(b) is a collinear chart of when the rear
wheel driving system 20 of the third embodiment operates in such a
way that the wheeled vehicle V travels straight ahead by four-wheel
drive (4WD), and arrows in the collinear chart indicate torques
acting on the elements. FIG. 16B(c) is a collinear chart of when
the rear wheel driving system 20 of the third embodiment operates
in such a way that the wheeled vehicle V travels straight ahead by
torque vectoring drive (TV), and arrows in the collinear than
indicate torques acting on the elements.
[0244] As shown in FIG. 16B(a), when the wheeled vehicle V is
running by front-wheel drive (FWD) with both the first and second
clutches CL1, CL2 left released, a power transmission path between
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state, and hence, no torque is
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr, whereby neither a left-right driving force sum nor a
left-right driving force difference is generated from the rear
wheel driving system 20.
[0245] As shown in FIG. 16B(b), when the wheeled vehicle V is
running by four-wheel drive (4WD) with the first and second
clutches CL1, CL2 put in the first state, a power transmission path
between the motor MOT and the carriers C1, C2 of the first and
second planetary gear mechanisms PL1, PL2 becomes a connected state
via the second output gear 35 and the second input gear 89, whereby
forward motor torque M is inputted from the motor MOT into the
carriers C1, C2. In normal first and second planetary gear
mechanisms PL1, PL2, in the event that forward torque is inputted
into carriers C1, C2, torque attempting to increase rotation speeds
is transmitted to sun gears S1, S2 and ring gears R1, R2. However,
in the first and second planetary gear mechanisms PL1, PL2 of this
embodiment, as has been described above, the ring gears R1, R2 are
controlled so as to rotate only in the opposite directions to each
other at the same rotation speed, and therefore, with the ring
gears R1, R2 acting as fulcrums, the forward motor torque M that is
inputted into the carriers C1, C2 that act as points of application
of force is transmitted to the sun gears S1, S2 that set as points
of action as forward left and right rear wheel torques T1, T2 that
result from multiplying motor torques M1, M2 by the gear ratios of
the first and second planetary gear mechanisms PL1, PL2. Since the
gear ratios of the first and second planetary gear mechanisms PL1,
PL2 are equal, the left and right rear wheel torques T1, T2 become
torques having equal absolute values and acting in the same
direction, and this generates a left-right driving force sum that
corresponds to a sum of the left and right rear wheel torques T1,
T2 (T1+T2), whereby a forward driving force is driven to the
wheeled vehicle V stably. A difference between the left and right
rear wheel torques T1, T2 (T1-T2) becomes zero, and with the first
and second clutch CL1, CL2 staying in the first state, there is no
such situation that a left-right driving force difference is
generated from the rear wheel driving system 20 due to the
generation of torque of the motor MOT, whereby no yaw moment is
given to the wheeled vehicle.
[0246] As shown in FIG. 16B(c), when the wheeled vehicle V is
running by torque vectoring drive (TV) with the first and second
clutches CL1, CL2 put in the second state, a power transmission
path between the motor MOT and the ring gears R1, R2 of the first
and second planetary gear mechanisms PL1, PL2 becomes a connected
state, whereby the motor torques M1, M2 having equal absolute
values and acting in the opposite directions are inputted front the
motor MOT into the ring gears R1, R2. Since in the carriers C1, C2,
motor torque distribution forces cancel (offset) each other, the
left and right rear wheel torques T1, T2 having equal absolute
values and acting in the opposite directions are generated in the
sun gears S1, S2, whereby a left-right driving force difference
corresponding a difference (T1-T2) between the left and right rear
wheels torques T1, T2 is generated, and a counterclockwise yaw
moment Y is given to the wheeled vehicle V in a stable fashion.
With the sum of the left and right rear wheel torques T1, T2
(T1+T2) becomes zero and the first and second clutches CL1, CL2
staying in the second state, a left-right driving force sum is not
generated from the rear wheel driving system 20 by the generation
of torque of the motor MOT, and no front-rear torque is given to
the wheeled vehicle V.
[0247] Thus, with this embodiment, as has been described
heretofore, the output shaft 21 of the motor MOT is connected to
the carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 and the ring gears R1, R2 of the first and
second planetary gear mechanisms PL1, PL2 so as to switch
therebetween selectively. Thus, with the single motor MOT, it
becomes possible to output the front-rear torques acting in the
same direction to the left and right rear wheels LWr, RWr or to
output the torques acting in opposite directions to the left rear
wheel LWr and the right rear wheel RWr without generating the
front-rear torque. Further, the torque of the motor MOT is inputted
to the different rotating elements of the first and second
planetary gear mechanism PL1, PL2 between when the front-rear
torques acting in the same direction are outputted to the left and
right rear wheels LWr, RWr and when the torques acting in the
opposite directions are outputted to the left rear wheel LWr and
the right rear wheel RWr without outputting the front-rear torque.
Thus, by changing the gear ratios of the sun gears S1, S2, the ring
gears R1, R2 and the carriers C1, C2, torque differences in
magnitude can be induced in the front-rear assist and the turning
assist.
Fourth Embodiment
[0248] Next, referring to FIG. 17, a rear wheel driving system 20
of a fourth embodiment will be described.
[0249] In this embodiment, a power transmission mechanism TM2
includes first and second clutches CL1, CL2 and two planetary gear
mechanisms, which are first and second planetary gear mechanisms
PL1, PL2. The first and second planetary gear mechanisms PL1, PL2
are each made up of a so-called single pinion planetary pear
mechanism and include, respectively, sun gears S1, S2, ring gears
R1, R2 and carriers C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring years R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, in this
embodiment, the carriers C1, C2 of the first and second planetary
gear mechanisms PL1, PL2 make up first rotating elements of the
first and second differential mechanisms, the ring gears R1, R2 of
the first and second planetary gear mechanisms PL1, PL2 make up
second rotating elements of the first and second differential
mechanisms, and the sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 make up third rotating elements
of the first and second differential mechanisms. The carriers C1,
C2 of the first and second planetary gear mechanisms PL1, PL2 are
connected to each other so as to rotate integrally and have a
common second input gear 89. This second input gear 89 meshes with
a hollow second output gear that surrounds an outer circumference
of an output shaft 21 of a motor MOT. The second output gear 35 is
provided on the output shaft 21 of the motor MOT so as to rotate
relatively thereto and is configured so as to rotate integrally
with or relative to the output shaft 21 through switching by the
first clutch CL1. In addition, the one gears R2, R1 are connected
to left and right rear wheels LWr, RWr via joints J1, J2,
respectively
[0250] In the sun gear S1 of the first planetary gear mechanism
PL1, large-diameter external teeth S1b that are formed integrally
with small-diameter external teeth S1a that are formed on an outer
circumferential surface thereof so as to mesh with the pinions P1
meshes with an idle gear 83 that meshes with a hollow first output
gear 25 that surrounds an outer circumference of the output shaft
21 of the motor MOT. In the sun gear S2 of the second planetary
gear mechanism PL2, large-diameter external teeth S2b that are
formed integrally with small-diameter external teeth S2a that are
formed on an outer circumferential surface thereof so as to mesh
with the pinions P2 meshes with the first output gear 25. The first
output gear 25 is provided on the output shaft 21 of the motor MOT
so as to rotate relatively thereto and is configured so as to
rotate integrally with or relative to the output shaft 21 through
switching by the second clutch CL2.
[0251] Namely, the sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the large-diameter
external teeth S1b with the idle gear 83, the meshing of the idle
gear 83 with the first output gear 25, and the meshing of the first
output gear 25 with the large-diameter external teeth S2b of the
sun gear S2. The two sun gears S1, S2 of the first and second
planetary gear mechanisms PL1, PL2 operate so as to rotate in
opposite directions to each other as a result of the sun gears S1,
S2 being connected together through the odd number of times of
meshing in the way described above.
[0252] Additionally, a gear ratio resulting from the meshing of the
large-diameter external teeth S1b of the sun gear S1 with the idle
gear 83 and the meshing of the idle gear 83 with the first output
gear 25 and a gear ratio resulting from the meshing of the
large-diameter external teeth S2b of the sun gear S2 with the first
output gear 25 are set so that absolute values thereof become equal
to each other. Consequently, the torque of the motor MOT is always
transmitted to the sun gears S1, S2 as torques having the equal
absolute values and acting in the opposite directions.
[0253] A second output gear 35 provided on the output shaft 21 of
the motor MOT and the first output gear 25 are disposed so as not
only to rotate relatively but also to face each other in the axial
direction. The second output gear 35 and the first output gear 25
are made to rotate integrally with or rotate relatively to the
output shaft 21 through switching by the first and second clutches
CL1, CL2. Namely, when applied or released, the first clutch CL1
connects or disconnects a power transmission between the output
shaft 21 of the motor MOT and the second output gear 35. When
applied or released, the second clutch CL2 connects or disconnects
a power transmission between the output shaft 21 of the motor MOT
and the first output gear 25. The first and second clutches CL1,
CL2 are each made up of a synchromesh mechanism that can be
switched over by a common actuator and can be switched over on the
same rotation axis, that is, the same rotation axis as the output
shaft 21.
[0254] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state to which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0255] In the state in which both the first and second clutches
CL1, CL2 are released, the first output gear 25 and the second
output gear 35 are not brought into connection with the output
shaft 21, whereby a power transmission path between the output
shaft 21 of the motor MOT and the first and second planetary gear
mechanisms PL1, PL2 becomes a disconnected state. When the first
and second clutches CL1, CL2 take the state in which the clutches
CL1, CL2 are both released, no torque is transmitted from the motor
MOT to the left and right rear wheels LWr, RWr, whereby neither a
left-right driving force sum nor a left-right driving force
difference is generated from the rear wheel driving system 20, this
enabling a front-wheel drive (FWD).
[0256] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the second output gear 35
is connected to the output shaft 21 of the motor MOT whereby a
power transmission path between the output shaft 21 and the
carriers C1, C2 of the first and second planetary gear mechanisms
PL1, PL2 becomes a connected state. When the first and second
clutches CL1, CL2 take the first state, torques of the same
magnitude are transmitted from the motor MOT to the left and right
rear wheels LWr, RWr in the same direction in the front-rear
direction, whereby a desired left-right driving force sum is
generated from the rear wheel driving system 20 while no left-right
driving force difference is generated therefrom, this enabling a
four-wheel drive (4WD).
[0257] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the first output
gear 25 is connected to the output shaft 21, whereby a power
transmission path between the output shaft 21 of the motor MOT and
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state by way of the first
output gear 25 and the idle gear 83. When the first and second
clutches CL1, CL2 take the second state torques of the same
magnitude are transmitted from the motor MOT to the left and right
rear wheels LWr, RWr in opposite directions in the front-rear
direction, whereby a desired left-right driving force difference is
generated from the rear wheel driving system 20 while no left-right
driving force sum is generated therefrom, this enabling a torque
vectoring drive (TV).
[0258] A collinear chart of the rear wheel driving system 20 of
this embodiment is represented by replacing the ring gear R1, R2
with the sun gears S1, S2, respectively. and sun gears S1, S2 with
the ring gears R1, R2, respectively, in FIG. 16B. The other
functions and advantages of this embodiment are similar to those of
the rear wheel driving system 20 of the third embodiment.
[0259] Thus, according to this embodiment, as has been described
heretofore, the output shaft 21 of the motor MOT is connected to
the carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 and the sun gears S1, S2 of the first and
second planetary gear mechanisms PL1, PL2 so as to switch
therebetween selectively. Thus, with the single motor MOT, it
becomes possible to output the front-rear torques acting in the
same direction to the left and right rear wheels LWr, RWr or to
output the torques acting in opposite directions to the left rear
wheel LWr and the right rear wheel RWr without generating the
front-rear torque. Further, the torque of the motor MOT is inputted
to the different rotating elements of the first and second
planetary gear mechanisms PL1, PL2 between when the front-rear
torques acting in the same direction are outputted to the left and
right rear wheels LWr, RWr and when the torques acting in the
opposite directions are outputted to the left rear wheel LWr and
the right rear wheel RWr without outputting the front-rear torque.
Thus, by changing the gear ratios of the sun gears S1, S2, the ring
gears R1, R2 and the carriers C1, C2, torque differences in
magnitude can be induced in the front-rear assist and the turning
assist.
Fifth Embodiment
[0260] Next, referring to FIG. 18A, a rear wheel driving system 20
of a fifth embodiment will be described.
[0261] In this embodiment, a power transmission mechanism TM2
includes first and second clutches CL1, CL2 and two planetary gear
mechanisms, which are first and second planetary gear mechanisms
PL1, PL2. The first and second planetary gear mechanisms PL1, PL2
are each made up of a so-called single pinion planetary gear
mechanism and include, respectively, sun gears S1, S2, ring gears
R1, R2 and carriers C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring gears R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, in this
embodiment, the ring gears R1, R2 of the first and second planetary
gear mechanisms PL1, PL2 make up first rotating elements of first
and second differential mechanisms, the sun gears S1, S2 of the
first and second planetary gear mechanisms PL1, PL2 make up second
rotating elements or the first and second differential mechanisms,
and carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 make up third rotating elements of the first
and second differential mechanisms. The ring gears R1, R2 of the
first and second planetary gear mechanisms PL1, PL2 are connected
to each other so as to rotate integrally and have common external
teeth R1b (R2b), and these external teeth R1b (R2b) mesh with a
hollow third output gear 87 that surrounds an outer circumference
of an output shaft 21 of a motor MOT. The third output near 87 is
provided on the output shaft 21 of the motor MOT so as to rotate
relatively thereto and is configured so as to rotate integrally
with or relative to the output shaft 21 through switching by the
first clutch CL1. In addition, the sun gears S1, S2 are connected
to left and right rear wheels LWr, RWr via joints respectively.
[0262] In the carrier C1 of the first planetary gear mechanism PL1,
a first input gear 91 that is formed integrally meshes with an idle
gear 83 that meshes with a first output gear 81 that is provided so
as to rotate integrally with the output shaft 21. In the carrier C1
of the second planetary gear mechanism PL2, a second input gear 93
that is formed integrally meshes with a hollow second output gear
85 that surrounds an outer circumference of the output shaft 21 of
the motor MOT. The second output gear 85 is provided on the output
shaft 21 of the motor MOT so as to rotate relatively thereto and is
configured so as to rotate integrally with or relative to the
output shaft 21 through switching by the second clutch CL1.
[0263] Namely, the carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the first input
gear 91 with the idle gear 83, the meshing of the idle gear 83 with
the first output gear 81 and the meshing of the second output gear
85 with the second input gear 93. The two carriers C1, C2 of the
first and second planetary gear mechanisms PL1, PL2 operate so as
to rotate in opposite directions to each other as a result of the
carriers C1, C2 being connected together through the odd number of
times of meshing in the way described above.
[0264] Additionally, a gar ratio resulting from the meshing of the
first input gear 91 of the carrier C1 with the idle gear 83 and the
meshing of the idle gear 83 with the first output gear 81 and a
gear ratio resulting from the meshing of the second input gear 93
of the carrier C2 with the second output gear 85 are set so that
absolute values thereof become equal to each other. Consequently,
torque of the motor MOT is always transmitted to the carriers C1,
C2 as torques having the equal absolute values and acting in the
opposite directions.
[0265] The third output gear 87 and the second output gear 85 that
are provided on the output shaft 21 of the motor MOT are disposed
so as not only to rotate relatively but also to face each other in
an axial direction. The third output gear 87 and the second output
gear 85 are made to rotate integrally or rotate relatively through
switching by the first and second clutches CL1, CL2. Namely, the
first clutch CL1 connects or disconnects the power transmission
between the output shaft 21 of the motor MOT and the third output
gear 87 by being applied or released. The second clutch CL2
connects or disconnects the power transmission between the output
shaft 21 of the motor MOT and the second output gear 85 by being
applied or released. The first and second clutches CL1, CL2 are
each made up of a synchromesh mechanism that can be switched over
by a common actuator and can be switched over on the same rotation
axis, that is, the same rotation axis as the output shaft 21.
[0266] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state in which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0267] In the state in which both the first and second clutches
CL1, CL2 are released, the output shaft 21 is not brought into
connection with either of the second output gear 85 and the third
output gear 87, whereby a power transmission path between the
output shaft 21 of the motor MOT and the first and second planetary
gear mechanisms PL1, PL2 becomes disconnected state. When the first
and second clutches CL1, CL2 take the state in which the clutches
CL1, CL2 are both released, no torque is transmitted from the motor
MOT to the left and right rear wheels LWr, RWr, whereby neither a
left-right driving force sum nor a left-right driving force
difference is generated from the rear wheel driving system 20, this
enabling a front-wheel drive (FWD).
[0268] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the output shaft 21 is
connected to the third output gear 87, whereby a power transmission
path between the output shaft 21 of the motor MOT and the ring
gears R1, R2 of the first and second planetary gear mechanisms PL1,
PL2 becomes a connected state. When the first and second clutches
CL1, CL2 take the first state, torques of the same magnitude are
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr in the same direction in the front-rear direction, whereby
a desired left-right driving force sum is generated from the rear
wheel driving system 20 while no left-right driving force
difference is generated therefrom, this enabling. a four-wheel
drive (4WD).
[0269] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the second output
gear 85 is connected to the output shaft 21 of the motor MOT,
whereby a power transmission path between the output shaft 21 and
the carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state. When the first and
second clutches CL1, CL2 take the second state, torques of the same
magnitude are transmitted from the motor MOT to the left and right
rear wheels LWr, RWr in opposite directions in the front-rear
direction, whereby a desired left-right driving force difference is
generated from the rear wheel driving system 20 while no left-right
driving force sum is generated therefrom, this enabling a torque
vectoring drive (TV).
[0270] In the rear wheel driving system 20 that is configured in
the way described heretofore, since the first and second planetary
gear mechanisms PL1, PL2 are configured in the way described above,
the sun gear S1, the carrier C1 and the ring gear R1 can transmit
power to one another, and rotation speeds thereof are in a
collinear relationship. Then, the sun gear S2, the carrier C2 and
the ring gear R2 can transmit power to one another, and rotation
speeds thereof are in a collinear relationship.
[0271] Since the ring gear R1 and the ring gear R2 are connected so
as to rotate integrally, rotation speeds of the ring gear R1 and
the ring gear R2 become equal to each other. The two carriers C1,
C2 of the first and second planetary gear mechanisms PL1, PL2
operate so as to rotate in opposite directions to each other at the
same rotation speed as a result of the carriers C1, C2 being
connected together through the odd number of times of meshing. This
means that to describe using a collinear chart in FIG. 18B, the
rotation speeds of the two carriers C1, C2 are controlled under a
relationship in which an imaginary line L1 that connects the two
carriers C1, C2 rotate on a point of intersection where the
imaginary line L1 intersects a zero rotation line L2 as a fulcrum
O.
[0272] FIG. 18B(a) is a collinear chart of when the rear wheel
driving system 20 of the fifth embodiment operates in such a way
that the wheeled vehicle V travels straight ahead by front-wheel
drive (FWD). FIG. 18B(b) is a collinear chart of when the rear
wheel driving system 20 of the fifth embodiment operates in such a
way that the wheeled vehicle V travels straight ahead by four-wheel
drive (4WD), and arrows in the collinear chart indicate torques
acting on the elements. FIG. 18B(c) is a collinear chart of when
the rear wheel driving system 20 of the fifth embodiment operates
in such a way that the wheeled vehicle V travels straight ahead by
torque vectoring drive (TV), and arrows in the collinear chart
indicate torques on the elements.
[0273] As shown in FIG. 18B(a), when the wheeled vehicle V is
running by front-wheel drive (FWD) with both the first and second
clutches CL1, CL2 left released, a power transmission path between
the motor MOT and the first and second planetary gear mechanisms
PL1, PL2 becomes a disconnected state, and hence, no torque is
transmitted from the motor MOT to the left and right rear wheels
LWr, RWr, whereby neither a left-right driving force sum nor a
left-right driving force difference is generated from the rear
wheel driving system 20.
[0274] As shown in FIG. 18B(b), when the wheeled vehicle V is
running by four-wheel drive (4WD) with the first and second
clutches CL1, CL2 put in the first state, a power transmission path
between the motor MOT and the ring gears R1, R2 of the first and
second planetary gear mechanisms PL1, PL2 becomes a connected state
via the third output gear 87, whereby reverse motor torque M is
inputted from the motor MOT into the ring gears R1, R2. In normal
first and second planetary gear mechanisms PL1, PL2, in the event
that reverse torque is inputted into ring gears R1, R2, torque
attempting to decrease rotation speeds is transmitted to sun gears
S1, S2 and carriers C1, C2. However, in the first and second
planetary gear mechanisms PL1, PL1 of this embodiment, as has been
described above, the carriers C1, C2 are controlled so as to rotate
only in the opposite directions to each other at the rotation speed
and therefore, with the carriers C1, C2 acting as fulcrums, the
reverse motor torque M that is inputted into the ring gears R1, R2
that act as points of application of force is transmuted to the sun
gears S1, S2 that act as points of action as forward left and right
rear wheel torques T1, T2 that result from multiplying motor
torques M1, M2 by the gear ratios of the first and second planetary
gear mechanisms PL1, PL2. Since the gear ratios of the first and
second planetary gear mechanisms PL1, PL2 are equal, the left and
right rear wheel torques T1, T2 become torques having equal
absolute values and acting in the same direction, and this
generates a left-right driving force sum that corresponds to a sum
of the left and right rear wheel torques T1, T2 (T1+T2), whereby a
forward driving force is given to the wheeled vehicle V stably. A
difference between the left and right rear wheel torques T1, T2
(T1-T2) becomes zero, and with the first and second clutch CL1, CL2
staying in the first state, there is no such situation that a
left-right driving force difference is generated from the rear
wheel driving system 20 due to the generation of torque of the
motor MOT, whereby no yaw moment is given to the wheeled vehicle
V.
[0275] As shown in FIG. 18B(c), when the wheeled vehicle is running
by torque vectoring drive (TV) with the first and second clutches
CL1, CL2 put in the second state, a power transmission path between
the motor MOT and the carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 becomes a connected state,
whereby the motor torques M1, M2 having equal absolute values and
acting in the opposite directions are inputted from the motor MOT
into the carriers C1, C2. Since in the ring gears R1, R2, motor
torque distribution forces cancel (offset) each other, the left and
right rear wheel torques T1, T2 having equal absolute values and
acting in the opposite directions are generated in the sun gears
S1, S2, whereby a left-right driving torque difference
corresponding a difference (T1-T2) between the left and right rear
wheels torques T1, T2 is generated, and a counterclockwise yaw
moment V is given to the wheeled vehicle V in a stable fashion.
With the sum of the left and right rear wheel torques T1, T2
(T1+T2) becomes zero and the first and second clutches CL1, CL2
staying in the second state, a left-right driving force sum is not
generated from the rear wheel driving system 20 by the generation
of torque of the motor MOT, and no front-rear torque is given to
the wheeled vehicle V.
[0276] Thus, according to this embodiment, as has been described
heretofore, the output shaft 21 of the motor MOT is connected to
the ring gears R1, R2 of the first and second planetary gear
mechanisms PL1, PL2 and the carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 so as to switch therebetween
selectively. Thus, with the single motor MOT it becomes possible to
output the front-rear torques acting in the same direction to the
left and right rear wheels LWr, RWr or to output the torques acting
in opposite directions to the left rear wheel LWr and the right
rear wheel RWr without generating the front-rear torque. Further,
the torque of the motor MOT is inputted to the different rotating
elements of the first and second planetary gear mechanisms PL1, PL2
between when the front-rear torques acting in the same direction
are outputted to the left and right rear wheels LWr, RWr and when
the torques acting in the opposite directions are outputted to the
left rear wheel LWr and the right rear wheel RWr without outputting
the front-rear torque. Thus, by changing the gear ratios of the sun
gears S1, S2, the ring gears R1, R2 and the carriers C1, C2, torque
differences in magnitude can be induced in the front-rear assist
and the turning assist.
Sixth Embodiment
[0277] Next, referring to FIG. 19, a rear wheel driving system 20
of a sixth embodiment will be described.
[0278] In this embodiment, a power transmission mechanism TM2
includes first and second clutches CL1, CL2 and two planetary gear
mechanisms, which are first and second planetary gear mechanisms
PL1, PL2. The first and second planetary gear mechanisms PL1, PL2
are each made up of a so-called single pinion planetary gear
mechanism and include, respectively, sun gear S1, S2, ring gears
R1, R2 and carriers C1, C2 which support pinions P1, P2 which mesh,
respectively, with the sun gears S1, S2 and the ring gears R1, R2
in such a way that the pinions P1, P2 rotate on their own axes and
revolve or walk around the sun gears S1, S2. Then, in this
embodiment, the sun gears S1, S2 of the first and second planetary
gear mechanisms PL1, PL2 make up first rotating elements of first
and second differential mechanisms, the ring gears R1, R2 of the
first and second planetary gear mechanisms PL1, PL2 make up second
rotating elements of the first and second differential mechanisms,
and the carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 make up third rotating elements of the first
and second differential mechanisms. Then, the sun gears S1, S2 of
the first and second planetary gear mechanisms PL1, PL2 are
connected to each other so as to rotate integrally via a connecting
shaft 23. The ring gears R1, R2 of the first and second planetary
gear mechanisms PL1, PL2 are connected to left and right rear
wheels LWr, RWr via joints S1, S2, respectively.
[0279] A second input gear 33 is provided on the connecting shaft
23 that connects together the sun gears S1, S2 of the first and
second planetary gear mechanisms PL1, PL2 equidistantly from the
sun gears S1, S2 as to rotate integrally with the sun gears S1, S2.
Then, this second input gear 33 meshes with a hollow third output
gear 87 that surrounds an outer circumference of the output shaft
21 of the motor MOT. The third output gear 87 is provided on the
output shaft 21 of the motor MOT so as to rotate relatively thereto
and is configured so as to rotate integrally with or relative to
the output shaft 21 through switching by the first clutch CL1.
[0280] In the carrier C1 of the first planetary gear mechanism PL1,
a first input gear 91 that is formed integrally meshes with an idle
gear 83 that meshes with a first output gear 81 that is provided so
as to rotate integrally with the output shaft 21. In the carrier C2
of the second planetary gear mechanism PL2, a second input gear 93
that is formed integrally meshes with a hollow second output gear
85 that surrounds an outer circumference of the output shaft 21 of
the motor MOT. The second output gear 85 is provided on the output
shaft 21 of the motor MOT so as to rotate relatively thereto and is
configured so as to rotate integrally with or relative to the
output shaft 21 through switching by the second clutch CL2.
[0281] Namely, the carriers C1, C2 of the first and second
planetary gear mechanisms PL1, PL2 are connected together through
three times of meshing including the meshing of the first input
gear 91 with the idle gear 83, the meshing of the idle gear 83 with
the first output gear 81 and the meshing of the second output gear
with the second input gear 93. The two carriers C1, C2 of the first
and second planetary gear mechanisms PL1, PL2 operate so as to
rotate in opposite directions to each other as a result of the
carriers C1, C2 being connected together through the odd number of
times of meshing in the way described above.
[0282] Additionally, a gear ratio resulting from the meshing of the
first input gear 91 of the carrier C1 with the idle gear 83 and the
meshing of the idle gear 83 with the first output gear 81 and a
gear ratio resulting from the meshing of the second input gear 93
of the carrier C2 with the second output gear 85 are set so that
absolute values thereof become equal to each other. Consequently,
torque of the motor MOT is always transmitted to the carriers C1,
C2 as torques having the equal absolute values and acting in the
opposite directions.
[0283] The third output gear 87 and the second output gear 85 that
are provided on an outer circumference of the output shaft 21 of
the motor MOT are disposed so as not only to rotate relatively but
also to face each other in an axial direction. The third output
gear 87 and the second output gear 85 are made to rotate integrally
or rotate relatively through switching by the first and second
clutches CL1, CL2. Namely, the first clutch CL1 connects or
disconnects the power transmission between the output shaft 21 of
the motor MOT and the third output gear 87 by being applied or
released. The second clutch CL2 connects or disconnects the power
transmission between the output shaft 21 of the motor MOT and the
second output gear 85 by being applied or released. The first and
second clutches CL1, CL2 are each made up of a synchromesh
mechanism that can be switched over by a common actuator and can be
switched over on the same rotation axis, that is, the same rotation
axis as the output shaft 21.
[0284] The first and second clutches CL1, CL2 are allowed to take
selectively one of a state as which the first and second clutches
CL1, CL2 are both released, a first state in which the first clutch
CL1 is applied while the second clutch CL2 is released, and a
second state in which the first clutch CL1 is released while the
second clutch CL2 is applied.
[0285] In the state in which both the first and second clutches
CL1, CL2 are released, the output shaft 21 is not brought into
connection with either of the second output gear 85 and the third
output gear 87, whereby a power transmission path between the
output shaft 21 of the motor MOT and the first and second planetary
gear mechanisms PL1, PL2 becomes disconnected state. When the first
and second clutches CL1, CL2 take the state in which the clutches
CL1, CL2 are both released, no torque is transmitted from the motor
MOT to the left and right rear wheels LWr, RWr, whereby neither a
left-right driving force sum nor a left-right driving force
difference is generated from the rear wheel driving system 20, this
enabling a front-wheel drive (FWD).
[0286] In the first state in which the first clutch CL1 is applied
while the second clutch CL2 is released, the output shaft 21 is
connected to the third output gear 87, whereby a power transmission
path between the output shaft 21 of the motor MOT and the sun
gears, S1, S2 of the first and second planetary gear mechanisms
PL1, PL2 becomes a connected state via a second input gear 33. When
the first and second clutches CL1, CL2 take the first state,
torques of the same magnitude are transmitted from the motor MOT to
the left and right rear wheels LWr, RWr to the same direction in
the front-rear direction, whereby a desired left-right driving
force sum is generated from the rear wheel driving system 20 while
no left-right driving force difference is generated therefrom, this
enabling a four-wheel drive (4WD).
[0287] In the second state in which the first clutch CL1 is
released while the second clutch CL2 is applied, the second output
gear 85 is connected to the output shaft 21 of the motor MOT,
whereby a power transmission path between the output shaft 21 and
the carriers C1, C2 of the first and second planetary gear
mechanisms PL1, PL2 becomes a connected state by way of the second
output gear 85, the first output gear 81, and the idle gear 83.
When the first and second clutches CL1, CL2 take the second state,
torques of the same magnitude are transmitted from the motor MOT to
the left and right rear wheels LWr, RWr in opposite directions in
the front-rear direction, whereby a desired left-right driving
force difference is generated from the rear wheel driving system 20
while no left-right driving force sum is generated therefrom, this
enabling a torque vectoring drive (TV).
[0288] A collinear chart of the rear wheel driving system 20 of
this embodiment is represented by replacing the sun gears S1, S2
with the ring gears R1, R2, respectively, and the ring gears R1, R2
with the sun gears S1, S2, respectively, in FIG. 18B. The other
functions and advantages of this embodiment are similar to those of
the rear wheel driving system 20 of the fifth embodiment.
[0289] Thus, according to this embodiment, as has been described
heretofore, the output shaft 21 of the motor MOT is connected to
the sun gears S1, S2 of the first and second planetary gear
mechanisms PL1, PL2 and the carriers C1, C2 of the first and second
planetary gnat mechanisms PL1, PL2 so as to switch therebetween
selectively. Thus, with the single motor MOT, it becomes possible
to output the front-rear torques acting in the same direction to
the left and right rear wheels LWr, RWr or to output the torques
acting in opposite directions to the left rear wheel LWr and the
right rear wheel RWr without generating the front-rear torque.
Further, the torque of the motor MOT is inputted to the different
rotating elements of the first and second planetary gear mechanisms
PL1, PL2 between when the front-rear torques acting in the same
direction are outputted to the left and right rear wheels LWr, RWr
and when the torques acting in the opposite directions are
outputted to the left rear wheel LWr and the right rear wheel RWr
without outputting the front-rear torque. Thus, by changing the
gear ratios of the sun gears S1, S2, the ring gears R1, R2 and the
carriers C1, C2, torque differences in magnitude can be induced in
the front-rear assist and the turning assist.
[0290] The present invention is not limited to the embodiments and
the modified examples which have been described heretofore and
hence can be modified or improved as required.
[0291] For example, in addition to the wheeled vehicle V depicted
in FIG. 1, as shown in FIG. 20, a capacitor CAP is disposed on an
electric power path between a switching mechanism SW and a
generator GEN, and the capacitor CAP is connected to a battery BATT
via a DC/DC convertor. In this way, providing the capacitor CAP on
the electric power path between the switching mechanism SW and the
generator GEN enables the capacitor CAP to assist in supplying
electric power that is insufficient in such a case that the
generator GEN cannot generate sufficient electric power as when an
engine ENG runs at low rotation speeds. In such a case, when the
wheeled vehicle V starts, a front-rear running assist is made by
means of the energy of the capacitor CAP, and thereafter, the
capacitor CAP may be switched to the generator GEN. Another battery
may be used in place of the capacitor CAP.
[0292] Additionally, a combination may be adopted in which a
generated voltage of the generator GEN differ from a charged
voltage of the battery BATT.
[0293] In addition, clutches of various configuration including a
friction clutch, a synchronized clutch and a dog clutch can be
adopted for the first and second clutches CL1, CL2.
[0294] Further, the driving system of the invention can be mounted
on propelling members of vehicle including wheels of various
wheeled vehicles such as a hybrid vehicle, a plug-in hybrid vehicle
and a range extender, propellers of aeroplanes and screws of
boats.
[0295] Further, in the embodiments described above, the planetary
gear mechanisms are described as being differential mechanisms.
However, other differential mechanisms may be adopted which
includes other types of planetary gear mechanisms using no
gearwheels such as a cyclone reducer, and differential
mechanisms.
[0296] This patent application is based on Japanese Patent
Application (No. 2013-259429) filed on Dec. 16, 2013, the contents
of which are incorporated herein by reference.
DESCRIPTION OF REFERENCE NUMERALS AND CHARACTERS
[0297] 20 rear sheet driving system (driving system) [0298] 21
output shaft [0299] V wheeled vehicle (vehicle) [0300] ENG engine
(another drive source) [0301] MOT motor (drive source) [0302] TM1,
TM2 power transmission mechanism [0303] PL1, PL2 first and second
planetary gear mechanisms (first and second differential
mechanisms) [0304] S1, S2 sun gear ( first rotating element, second
rotating element, third rotating element) [0305] C1, C2 carrier
(first rotating element, second rotating element, third rotating
element) [0306] R1, R2 ring gear (first rotating element, second
rotating element, third rotating element) [0307] LWr left rear
wheel (left driving portion) [0308] RWr right rear wheel (right
driving portion) [0309] CL1 first clutch (first switching
mechanism, switching unit) [0310] CL2 second clutch (second
switching mechanism, switching unit) [0311] GEN generator (first
energy delivery and receipt unit) [0312] CAP capacitor (first
energy delivery and receipt unit) [0313] BATT battery (second
energy delivery and receipt unit)
* * * * *